(19)
(11)EP 3 160 061 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
15.05.2019 Bulletin 2019/20

(21)Application number: 15853952.8

(22)Date of filing:  23.10.2015
(51)Int. Cl.: 
H04B 10/572  (2013.01)
H01S 5/024  (2006.01)
H01S 5/0687  (2006.01)
(86)International application number:
PCT/CN2015/092698
(87)International publication number:
WO 2016/066064 (06.05.2016 Gazette  2016/18)

(54)

OPTICAL TRANSMITTER, WAVELENGTH ALIGNMENT METHOD AND PASSIVE OPTICAL NETWORK SYSTEM

OPTISCHER SENDER, WELLENLÄNGENZUWEISUNGSVERFAHREN UND PASSIVES OPTISCHES NETZWERKSYSTEM

ÉMETTEUR OPTIQUE, PROCÉDÉ D'ALIGNEMENT DE LONGUEUR D'ONDE ET SYSTÈME DE RÉSEAU OPTIQUE PASSIF


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 30.10.2014 CN 201410603572

(43)Date of publication of application:
26.04.2017 Bulletin 2017/17

(73)Proprietor: Huawei Technologies Co., Ltd.
Longgang District Shenzhen, Guangdong 518129 (CN)

(72)Inventors:
  • LIAO, Zhenxing
    Shenzhen, Guangdong 518129 (CN)
  • WANG, Lingjie
    Shenzhen, Guangdong 518129 (CN)
  • ZHOU, Min
    Shenzhen, Guangdong 518129 (CN)
  • HUANG, Jing
    Shenzhen, Guangdong 518129 (CN)

(74)Representative: Thun, Clemens 
Mitscherlich PartmbB Patent- und Rechtsanwälte Sonnenstraße 33
80331 München
80331 München (DE)


(56)References cited: : 
EP-A2- 1 215 832
CN-A- 103 261 935
CN-U- 202 886 658
US-A1- 2006 222 025
WO-A1-2010/040377
CN-A- 103 281 129
US-A1- 2005 013 614
US-A1- 2009 097 863
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to the field of optical fiber communications, and in particular, to an optical transmitter, a wavelength alignment method, and a passive optical network system.

    BACKGROUND



    [0002] Based on increasing requirements of users on bandwidth, a PON (Passive Optical Network) system, which is extremely competitive, of an optical fiber access network that is used as a new generation broadband access network becomes an object mainly used by the users. Generally, the PON system includes one OLT (Optical Line Terminal) located in a central office, one ODN (Optical Distribution Network) used for bifurcation/coupling or multiplexing/demultiplexing, and a plurality of ONUs (Optical Network Unit).

    [0003] However, with increasingly faster development of various broadband services, such as a video conference, a 3D television, mobile backhaul, an interactive game, and a cloud service, a line rate in the PON system also needs to be improved constantly. In particular, the existing EPON system and GPON system need to be gradually upgraded to high-speed (a speed of 10 G or above) PON systems. However, for a PON system of a high modulation rate of 10 G or above, an obvious dispersion penalty is caused even within a transmission distance of 20 km, causing that quality of a transmit signal is seriously degraded and system receiving sensitivity is seriously reduced. A dispersion penalty of transmission is closely related to a transmission and modulation manner of the PON system, different modulation schemes cause different frequency chirps of an optical signal, and this directly causes different introduced dispersion penalties. Currently, an OLT-side optical module of a PON system of 10 G high-rate modulation mainly uses: a transmission and external modulation manner of an EML (Electro-absorption Modulated Laser) and a transmission and direct modulation manner of a DML (Directly Modulated Laser).

    [0004] The transmission and external modulation manner of the EML refers to that: an output light of a laser is directly injected into an external modulator, a modulation signal controls the external modulator, and an acoustooptic effect and an electro-optic effect are used to enable a parameter, such as intensity of output light of the external modulator, to change with the signal. Because the laser works in a static direct current state, an output signal has a small frequency chirp and high transmission performance. Therefore, at the present stage, 10 G PON OLT-side optical modules all use a transmission manner of an EML (Electro-absorption Modulated Laser). However, a cost of the EML is high, and an insertion loss is greater (6 dB to 8 dB), causing that transmission power consumption remains at a high level.

    [0005] The transmission and direct modulation manner of the DML refers to modulating output of a semiconductor laser by changing an injected current, a structure of the DML is simple and is easy to implement, and a cost is low. However, a modulation current causes a change in an active layer refractive index, causing that a phase of a light is modulated, and therefore, an operating frequency is broadened, that is, a relatively great frequency chirp exists, and with increase of a modulation rate, a chirp phenomenon becomes more serious. Therefore, it is difficult to directly use the traditional DML as a transmitter of a high-speed OLT optical module of 10 G or above.

    [0006] Therefore, an optical transmitter with a high modulation rate that is based on a DML technology, has a low cost, consumes less power, and can reduce the chirp phenomenon is urgently needed, so as to resolve engineering problems currently facing the 10 G-PON and facing a higher-rate PON system in the future.

    [0007] EP1215832 discloses a similar prior art optical transmitter.

    SUMMARY



    [0008] In view of this, embodiments of the present invention provide an optical transmitter, a wavelength alignment method, and a passive optical network system, so as to resolve a problem of serious chirp phenomenon that is caused because in the prior art a DML cannot adapt to a 10 G-PON and a transmitter of a higher-rate PON system.

    [0009] To achieve the foregoing objective, the present invention provides the following technical solutions:

    [0010] In a first aspect an optical transmitter is provided comprising:

    a transmitter optical, TO, base, a thermoelectric cooler, TEC, and a heat sink that are transverse and are connected sequentially from bottom to top;

    a first monitor photodiode, MPD, a 10 Gigabits per second-directly modulated laser , 10 Gbps-DML, a collimation lens, and a narrowband optical filter that are disposed above the heat sink, wherein the first MPD is integrated into the 10 Gbps-DML, the collimation lens is located between the 10 Gbps-DML and the narrowband optical filter, and one side, which faces the collimation lens, of the narrowband optical filter is connected to the heat sink at a preset tilt angle;

    a second MPD that is disposed above the narrowband optical filter and connected to the narrowband optical filter; and

    a wavelength locking monitoring circuit connected to a TO pin disposed at one side of the TO base, and a wavelength locking control circuit connected to the wavelength locking monitoring circuit, wherein

    a forward emitted light emitted by the 10 Gbps-DML laser is input to the narrowband optical filter through the collimation lens, and a backward emitted light emitted by the 10 Gbps-DML is input to the first MPD; and the narrowband optical filter reflects a forward transmitted light, which is split from the forward emitted light, to the second MPD connected to the narrowband optical filter;

    the first MPD receives and monitors a first optical power of the backward emitted light, and the second MPD receives and monitors a second optical power of the forward transmitted light; and

    the wavelength locking monitoring circuit that receives the first optical power and the second optical power by using the TO pin separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the first optical power and the second optical power, and sends a comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of the TEC to perform wavelength alignment.



    [0011] In a first implementation form of the first aspect the wavelength locking monitoring circuit that separately compares the variation of the wavelength locking factor K0 with the corresponding threshold based on variations of the first optical power and the second optical power, and sends the comparison result to the wavelength locking control circuit comprises:

    the wavelength locking monitoring circuit being configured to: calculate a wavelength locking factor K4 based on an average value of measurement values of first optical powers of the first MPD and an average value of measurement values of second optical powers of the second MPD, wherein the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset d degrees Celsius and reducing the temperature of the TEC by preset d degrees Celsius, and determine whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a first threshold; if yes, calculate a wavelength locking factor K5 based on an average value of measurement values of first optical powers of the first MPD and an average value of measurement values of second optical powers of the second MPD, wherein the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and determine whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a second threshold; and if yes, determine that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 Gbps-DML drift, and enable the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 Gbps-DML to be aligned with the wavelength locking factor K0, wherein

    preset e degrees Celsius is greater than preset d degrees Celsius.



    [0012] In a second aspect a wavelength alignment method, applied to the above optical transmitter is provided, wherein the method comprises:

    according to a preset time interval and based on an initial working point, controlling a wavelength locking control circuit to adjust a temperature of the TEC to increase preset d degrees Celsius and reduce preset d degrees Celsius, and acquiring an average value of measurement values of first optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of measurement values of second optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K4;

    determining whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a first threshold, and if not, going back to the step of calculating a wavelength locking factor K4 according to a preset time interval and based on the initial working point; and

    if yes, based on the initial working point, controlling the wavelength locking control circuit to adjust the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and acquiring an average value of the measurement values of the first optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of the measurement values of the second optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K5, wherein preset e degrees Celsius is greater than preset d degrees Celsius;

    determining whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a second threshold, and if not, going back to the step of calculating a wavelength locking factor K4 according to a preset time interval and based on the initial working point; and

    if yes, determining that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 Gbps-DML drift, and enabling the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 Gbps-DML to be aligned with the wavelength locking factor K0.



    [0013] In a first implementation form of the second aspect the obtaining the wavelength locking factor K0 through initial calculation comprises:

    calculating a wavelength locking factor K0 according to a TEC that has a determined temperature and that is obtained by initializing the 10 Gbps-DML, and the measurement values of the first optical power of the first MPD and the second optical power of the second MPD; and

    the initializing the 10 Gbps-DML comprises:

    testing a correspondence between a power P of a tube core of the DML and a drive current I, and setting an initial bias current Ib and a modulation current Im of the DML according to the correspondence;

    in a case of adding a 10 Gbps-signal, scanning the temperature of the TEC, and searching for a greatest power value of the 10 Gbps-DML;

    increasing the temperature of the TEC according to the greatest power value, and measuring a current optical output power, an extinction ratio ER, and an eye pattern;

    when the current optical output power is greater than 2 dBm, determining that a corresponding temperature of the TEC is a lower limit initial value of an effective wavelength region of the narrowband optical filter;

    when the extinction ratio ER is greater than a preset ratio, and the eye pattern meets a standard mask, determining that the corresponding temperature of the TEC is an upper limit initial value of the effective wavelength region of the narrowband optical filter; and

    within a range formed by the upper limit initial value and the lower limit initial value, measuring whether sensitivity of a boundary point and an intermediate zone of the range is less than preset sensitivity;

    if yes, setting a middle point in the range formed by the upper limit initial value and the lower limit initial value as an initial working point, and preliminarily determining that an initial status of the 10 Gbps-DML comprises the temperature of the TEC at the initial working point, and the measurement values of the first optical power of the first MPD and the second optical power of the second MPD; and

    if not, based on the boundary point, narrowing the boundary point of the effective wavelength region inwards, until it is found through measurement that sensitivity of a narrowed boundary point and the intermediate zone is less than the preset sensitivity.



    [0014] It can be seen from the foregoing technical solutions that, compared with the prior art, the embodiments of the present invention disclose an optical transmitter, a wavelength alignment method, and a passive optical network system, for the foregoing optical transmitter disclosed in the embodiments of the present invention, a 10 G-DML, an MPD 1, an MPD 2, a collimation lens, and a narrowband optical filter are disposed in a TO thereof; therefore, monitoring of an optical power can be achieved, a component, such as an optical isolator or a beam splitter in the TO is saved, and packaging of a DML and a filter in the TO is achieved in a manner of a low cost. In addition, received optical powers are monitored by using the MPD 1 and the MPD 2, the detected optical powers are output to a wavelength locking monitoring circuit by using a TO pin, variations, which are detected by the wavelength locking monitoring circuit, of the foregoing detected optical powers and a variation of a wavelength locking factor K0 are separately compared with corresponding thresholds, and a comparison result are sent to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a TEC to perform wavelength alignment. In the embodiments of the present invention, wavelength locking control is performed on a wavelength of a 10 G-DML and a filter by using a novel wavelength monitor loop, so that the optical transmitter disclosed in the embodiments of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    BRIEF DESCRIPTION OF DRAWINGS



    [0015] To describe the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show merely the embodiments of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

    FIG. 1 is a schematic structural diagram of an optical transmitter according to Embodiment 1 of the present invention;

    FIG. 2 is a flowchart of a wavelength alignment method according to Embodiment 2 of the present invention;

    FIG. 3 is a curve comparison diagram of optical powers that are monitored by an MPD 1 and an MPD 2 in a wavelength alignment method according to Embodiment 2 of the present invention;

    FIG. 4 is a flowchart of a wavelength alignment method according to Embodiment 2 to Embodiment 4 of the present invention;

    FIG. 5 is a schematic structural diagram of an optical transmitter according to Embodiment 5 of the present invention;

    FIG. 6 is a curve comparison diagram of optical powers that are monitored by an MPD 1 and an MPD 2 in a wavelength alignment method according to Embodiment 6 of the present invention;

    FIG. 7 is a flowchart of a wavelength alignment method according to Embodiment 6 of the present invention;

    FIG. 8 is a schematic structural diagram of an optical transmitter according to Embodiment 7 of the present invention;

    FIG. 9 is a flowchart of a wavelength alignment method according to Embodiment 8 of the present invention; and

    FIG. 10 is a schematic structural diagram of a passive optical network system according to an embodiment of the present invention.


    DESCRIPTION OF EMBODIMENTS



    [0016] For ease of reference and clarity, descriptions, abbreviations, or acronyms of technical terms used hereinafter are summarized as follows:

    PON: Passive Optical Network, passive optical network; LD: Laser Diode, laser diode;

    OLT: Optical Line Terminal ,optical line terminal; BS: Beam Splitter, beam splitter;

    DML: Directly Modulated Laser, directly modulated laser; Isolator: optical isolator;

    MPD: Monitor Photodiode, monitor photodiode;

    ODN: Optical Distribution Network, optical distribution network;

    ONU: Optical Network Unit, optical network unit;

    TO: Transmitter Optical, laser transmitter; Etalon FILTER, Etalon filter;

    DFB: Distributed Feedback Laser, distributed feedback laser;

    CML: Chirp Managed Laser, chirp managed laser;

    ER: Extinction Ratio, extinction ratio; TEC: Thermoelectric Cooler, thermoelectric cooler.



    [0017] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some but not all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

    [0018] It can be seen from the background that, a transmission and direct modulation manner of a traditional DML refers to modulating output of a semiconductor laser by changing an injected current, a structure of the traditional DML is simple and is easy to implement, and a cost is low. However, a modulation current causes a change in an active layer refractive index, causing that a phase of a light is modulated, and therefore, an operating frequency is broadened, a relatively great frequency chirp further exists, and with increase of a modulation rate, a chirp phenomenon becomes more serious. Apparently, it is difficult to directly use the traditional DML as a transmitter of a high-speed OLT optical module of 10 G or above. Therefore, the embodiments of the present invention disclose several novel optical transmitters that have a novel structure of packaging a DML and an Etalon component in a minimized manner, and wavelength alignment methods corresponding to the optical transmitters, so that the optical transmitters can be used as transmitters of high-speed OLT optical modules of 10 G or above, which are described in detail in the following embodiments.

    Embodiment 1



    [0019] FIG. 1 is an optical transmitter according to this embodiment not forming part of the present invention, mainly including:

    a TO base 1, a TEC, and a heat sink 2 that are transverse and are connected sequentially from bottom to top;

    a TO pin 3 whose one side is connected to one end of the TO base 1;

    a second MPD (which is shown as an MPD 2 in FIG. 1), a 10 G-DML, a collimation lens 4, and a narrowband optical filter 5 that are disposed above the heat sink 2, where the MPD 2 and the collimation lens 4 are located at two sides of the 10 G-DML, and the narrowband optical filter 5 is located at the other side of the collimation lens 4, and one side, which faces the collimation lens 4, of the narrowband optical filter 5 is connected to the heat sink 2 at preset tilt angle;

    a first MPD (which is shown as an MPD 1 in FIG. 1) disposed above the narrowband optical filter 5; and

    a wavelength locking monitoring circuit 6 connected to the TO pin 3 disposed at one side of the TO base 1, and a wavelength locking control circuit 7 connected to the wavelength locking monitoring circuit 6, where

    a forward emitted light emitted by the 10 G-DML is input to the narrowband optical filter 5 through the collimation lens 4, and a backward emitted light emitted by the 10 G-DML is input to the MPD 2; and the narrowband optical filter 5 splits the forward emitted light into a forward transmitted light and a backward reflected light, transmits, at a preset elevation angle, the backward reflected light to the MPD 2, and partially reflect the forward transmitted light to the MPD 1 connected to the narrowband optical filter 5, where

    the forward transmitted light herein may refer to the entire forward transmitted light, or may refer to one part of the forward transmitted light;

    the MPD 1 receives and monitors a first optical power of the forward transmitted light, and the MPD 2 receives and monitors a second optical power that is after the backward emitted light and the backward reflected light complement each other; and

    the wavelength locking monitoring circuit 6 that receives the first optical power and the second optical power by using the TO pin 3 separately compares detected variations of the first optical power and the second optical power and a variation of a wavelength locking factor K0 with corresponding thresholds, and sends a comparison result to the wavelength locking control circuit 7, to enable the wavelength locking control circuit 7 to adjust, according to the comparison result and by using the TO pin 3, a temperature of the TEC.



    [0020] Preferably, the wavelength locking monitoring circuit 6 that separately compares detected variations of the first optical power and the second optical power and a variation of a wavelength locking factor K0 with corresponding thresholds, and sends a comparison result to the wavelength locking control circuit 7 includes:

    when the variations of the first optical power and the second optical power and the variation of the wavelength locking factor K0 exceed the corresponding thresholds, comparing the first optical power with a first optical power detected last time, and comparing the second optical power with a second optical power detected last time, and if the first optical power is less than the first optical power detected last time, and the second optical power is greater than the second optical power detected last time, obtaining a first comparison result, and sending the first comparison result to the wavelength locking control circuit; otherwise, obtaining a second comparison result, and sending the second comparison result to the wavelength locking control circuit, where

    the first comparison result is that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 G-DML drift towards a longer wave; and the second comparison result is that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 G-DML drift towards a shorter wave.



    [0021] Similarly, the wavelength locking control circuit 7 that adjusts, according to the comparison result and by using the TO pin, a temperature of the TEC to perform wavelength alignment includes: when the first comparison result is received, sending, by using the TO pin, an instruction for reducing the temperature of the thermoelectric cooler TEC, and controlling a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0; or when the second comparison result is received, sending, by using the TO pin, an instruction for increasing the temperature of the TEC, and controlling a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0.

    [0022] Based on the optical transmitter disclosed in this embodiment a BS is built in the narrowband optical filter 5, and one surface, which is in contact with the heat sink 2, of the narrowband optical filter 5 is machined to be at an oblique angle, and the narrowband optical filter may also be an Etalon FILTER having an obliquely built-in BS; and the 10 G-DML may also be a 10 G-DFB.

    [0023] Based on this, the forward emitted light emitted by the 10 G-DML is input to the narrowband optical filter 5 through the collimation lens 4, main energy of the forward emitted light enters an optical fiber through the narrowband optical filter 5 to transmit a data signal, some energy, that is, the forward transmitted light, is reflected by a BS built in the narrowband optical filter 5 to the MPD 1, and the MPD 1 monitors an optical power of the received forward transmitted light.

    [0024] In addition, one surface, which is in contact with the heat sink 2, of the narrowband optical filter 5 is machined to be at an oblique angle, and therefore, an incident surface of the narrowband optical filter 5 uses one part of the forward emitted light as a backward reflected light and reflects, at an elevation angle, the backward reflected light to the MPD 2 that is at the rear of the 10 G-DML (which may also be considered to be at the rear of an LD chip). Because there is an elevation angle (where the elevation angle has a relationship with the foregoing oblique angle between the narrowband optical filter 5 and the heat sink, where a greater oblique angle indicates a greater elevation angle), the backward reflected light is not injected into the 10 G-DML (not input to the LD chip), which, in other words, does not interfere with normal operation of the 10 G-DML. At this time, the MPD 2 also receives a backward emitted light emitted backwards from the 10 G-DML.

    [0025] Specifically, the optical power monitored by the MPD 2 has two parts, including: the backward emitted light (which may also be referred to as a backward direct current light) of the 10 G-DML and a backward reflected light (which may also be referred to as a periodically reflected light of the narrowband optical filter), which is reflected by the narrowband optical filter, in the forward emitted light of the 10 G-DML; and therefore, the MPD in fact monitors an optical power that is after the backward emitted light and the backward reflected light complement each other.

    [0026] For the foregoing optical transmitter disclosed in this embodiment of the present invention, a 10 G-DML, an MPD 1, an MPD 2, a collimation lens, and a narrowband optical filter are disposed in a TO thereof; therefore, monitoring of an optical power can be achieved, a component, such as an optical isolator or a beam splitter in the TO is saved, and packaging of a DML and a filter in the TO is achieved in a manner of a low cost. In addition, a first optical power of a forward transmitted light is monitored by the MPD 1, a second optical power that is after a backward emitted light and a backward reflected light complement each other is monitored by the MPD 2, the detected optical powers are output to a wavelength locking monitoring circuit by using a TO pin, variations, which are detected by the wavelength locking monitoring circuit, of the first optical power and the second optical power and a variation of a wavelength locking factor K0 are separately compared with corresponding thresholds, and a comparison result are sent to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a TEC. In this embodiment of the present invention, wavelength locking control is performed on a wavelength of a 10 G-DML and a narrowband optical filter by using a novel wavelength monitor loop, so that the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    Embodiment 2



    [0027] Based on an optical transmitter disclosed in Embodiment 1 based on the optical transmitter, this embodiment further correspondingly discloses a wavelength alignment method. The method is based on a schematic structural diagram of an optical transmitter shown in FIG. 1, and as shown in FIG. 2, mainly includes the following steps:

    [0028] Step S101. A wavelength locking monitoring circuit receives, by using a TO pin, a first optical power, which is monitored by a first MPD, of a forward transmitted light, and a second optical power that is monitored by a second MPD and that is after a backward emitted light and a backward reflected light complement each other, and uses a ratio of the first optical power to the second optical power or a difference between the first optical power and the second optical power as a wavelength locking factor K0.

    [0029] During performing of step S101, based on the optical transmitter disclosed in FIG. 1, the forward transmitted light monitored by the first MPD is one part of a forward emitted light emitted by a 10 G-DML. Specifically: the forward emitted light emitted by the 10 G-DML is input to the narrowband optical filter 5 through a collimation lens 4, the forward emitted light is split into two parts in a narrowband optical filter 5, one part of energy thereof is used as the forward transmitted light and is reflected by a BS built in the narrowband optical filter 5 to an MPD 1, and the MPD 1 monitors an optical power of the received forward transmitted light.

    [0030] The other part is used as a backward reflected light and is reflect at an elevation angle to an MPD 2 at the rear of the 10 G-DML, and the MPD 2 receives a backward emitted light emitted by the 10 G-DML; and therefore, during performing of step S101, an optical power monitored by the second MPD is an optical power that is after the received backward emitted light and the backward reflected light complement each other. It should be noted that "first" and "second" herein are used only for differentiating different monitored optical powers.

    [0031] FIG. 3 is a spectrum tendency chart showing a forward transmitted light monitored by an MPD 1 and a fact after a backward emitted light monitored by the MPD 2 and a backward reflected light complement each other. It can be seen from FIG. 3 that, lights monitored by the MPD 1 and the MPD 2 complement each other, where an X-axis indicates a value of a temperature of the TEC, and a Y-axis indicates a value of an optical power that corresponds to the temperature of the TEC.

    [0032] Step S102. The wavelength locking monitoring circuit monitors whether variations of the first optical power and the second optical power and a variation of the wavelength locking factor K0 exceed corresponding thresholds; if the variations exceed the corresponding thresholds, perform step S103, and if the variations do not exceed the corresponding thresholds, go back to perform step S101.

    [0033] In step S102, the wavelength locking monitoring circuit monitors variations of a first optical power and a second optical power, and a variation of a wavelength locking factor K0 that are received in real time, and determines in real time whether the variation of the first optical power exceeds a corresponding threshold, and determines whether the variation of the second optical power exceeds a corresponding threshold, and whether the variation of the wavelength locking factor K0 exceeds a corresponding threshold. It should be noted that the respective corresponding thresholds with which the foregoing variations are compared may be the same or may be different. In addition, a wavelength locking factor K0 determined each time is a ratio of a currently detected first optical power to a currently detected second optical power or a difference between a currently detected first optical power and a currently detected second optical power.

    [0034] Step S103. When the variations of the first optical power and the second optical power and the variation of the wavelength locking factor K0 exceed the corresponding thresholds, compare the first optical power with a first optical power detected last time, compare the second optical power with a second optical power detected last time, and send a comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a thermoelectric cooler TEC to perform wavelength alignment.

    [0035] During performing of step S103, it is determined that the variations of the first optical power and the second optical power that are detected or received by the wavelength locking monitoring circuit at this time and the variation of the wavelength locking factor K0 exceeds the corresponding thresholds. Therefore, if step S103 is performed, a value actually corresponding to the variation is determined, that is, the first optical power is compared with a first optical power detected last time, the second optical power is compared with a second optical power detected last time, and a comparison result obtained through the comparison are sent to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, the temperature of the thermoelectric cooler TEC to perform wavelength alignment.

    [0036] By using the wavelength alignment method disclosed in this embodiment of the present invention, wavelength locking control can be performed on a wavelength of a10 G-DML and a narrowband optical filter, so that a corresponding optical transmitter can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    Embodiment 3



    [0037] Based on an optical transmitter disclosed in Embodiment 1 and a wavelength alignment method disclosed in Embodiment 2 of the present invention, before step S101 of receiving, by a wavelength locking monitoring circuit by using a TO pin, a first optical power, which is monitored by a first MPD, of a forward transmitted light, and a second optical power that is monitored by a second MPD and that is after a backward emitted light and a backward reflected light complement each other is performed, the following steps are further included:

    [0038] Step S100. The wavelength locking monitoring circuit reads a temperature of a TEC at a standard working point, a first standard optical power M1 of the first MPD, and a second standard optical power M2 of the second MPD, calculates an average optical power Pa with t*M1+M2 in a preset effective wavelength region, and uses Pa as input of an automatic optical power control loop, where an input end of the automatic power control loop is connected to the first MPD or the second MPD, and t is a preset proportion coefficient.

    [0039] In step S100, a preset effective wavelength region is formed by combining the 10 G-DML with the narrowband optical filter, that is, relative locations of wavelengths of the 10 G-DML and the narrowband optical filter are in an area in a range, and a preset effective wavelength region is determined by an overall performance test.

    [0040] In step S100, during calculation of the average optical power Pa, because the first standard optical power M1 and the second standard optical power M2 have a complementary relationship, M1 multiplied by the preset proportion coefficient t then plus M2 approximately makes a constant, and the average optical power Pa is calculated based on the constant, which can ensure stability of an original optical power. Subsequently, the average optical power Pa is used as input of the automatic optical power control loop. Because the input end of the automatic power control loop is connected to the first MPD or the second MPD, based on the stable original optical power, during performing of subsequent step S101 to step S103 shown in FIG. 2, a forward emitted light and a backward emitted light that are emitted by an MPD 1 and an MPD 2 to the 10 G-DML are not affected.

    Embodiment 4



    [0041] Based on an optical transmitter disclosed in Embodiment 1 and a wavelength alignment method disclosed in Embodiment 2 and/or Embodiment 3, in step S103, the comparing the first optical power with a first optical power detected last time, comparing the second optical power with a second optical power detected last time, and sending a comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a thermoelectric cooler TEC specifically includes the following steps:

    Step S1031. Compare the first optical power with the first optical power detected last time, and compare the second optical power with the second optical power detected last time; and if the first optical power is reduced and the second optical power is increased, perform step S1032; otherwise, perform step S1034.

    Step S1032. If the first optical power is less than the first optical power detected last time, and the second optical power is greater than the second optical power detected last time, obtain a first comparison result, where the first comparison result is that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 G-directly modulated laser DML drift towards a longer wave.

    Step S1033. Send the first comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to send, by using the TO pin, an instruction for reducing the temperature of the thermoelectric cooler TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0, where the wavelength locking factor K0 is a ratio of the current first optical power to the current second optical power or a difference between the current first optical power and the current second optical power.

    Step S1034. If the first optical power is less than the first optical power detected last time, and the second optical power is less than or equal to the second optical power detected last time a; or if the first optical power is greater than or equal to the first optical power detected last time, and the second optical power is greater than the second optical power detected last time; or if the first optical power is greater than the first optical power detected last time, and the second optical power is less than the second optical power detected last time, obtain a second comparison result, where the second comparison result is that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 G-DML drift towards a shorter wave.

    Step S1035. Send the second comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to send, by using the TO pin, an instruction for increasing the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0, where the wavelength locking factor K0 is a ratio of the current first optical power to the current second optical power or a difference between the current first optical power and the current second optical power.



    [0042] Summing up the foregoing process of the wavelength alignment method in Embodiment 2 to Embodiment 4, a specific flowchart is shown in FIG. 4.

    [0043] In the wavelength alignment method disclosed in Embodiment 2 to Embodiment 4, a first optical power of a forward transmitted light is monitored by an MPD 1, a second optical power that is after a backward emitted light and the backward reflected light complement each other is monitored by an MPD 2, the detected optical powers are output to a wavelength locking monitoring circuit by using a TO pin, variations, which are detected by the wavelength locking monitoring circuit, of the first optical power and the second optical power and a variation of a wavelength locking factor K0 are separately compared with corresponding thresholds, and a comparison result are sent to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a TEC to perform wavelength alignment. In this embodiment of the present invention, a narrowband optical filter that has an oblique angle with a heat sink is used, and a backward reflected light thereof is directly reflected to an MPD 1 without interfering with an LD or a 10 G-DML; and in addition, wavelength locking control is performed on a wavelength of the 10 G-DML and a filter by using a novel wavelength monitor loop, so that an optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    [0044] This embodiment further discloses an optical transmitter, where similarly, a 10 G-DML, an MPD 1, an MPD 2, a collimation lens, and a narrowband optical filter are disposed in a TO; therefore, monitoring of an optical power can be achieved, and the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future, which is specifically described as follows.

    Embodiment of the invention



    [0045] FIG. 5 is an optical transmitter according to the present invention, mainly including:
    a TO base 1, a TEC, and a heat sink 2 that are transverse and are connected sequentially from bottom to top;

    a TO pin 3 whose one side is connected to one end of the TO base 1;

    a first MPD (which is shown as an MPD 1 in FIG. 5), a 10 G-DML, a collimation lens 4, and a narrowband optical filter 5 that are disposed above the heat sink 2, where the MPD 1 is integrated into the 10 G-DML, the collimation lens 4 is located between the 10 G-DML and the narrowband optical filter 5, and one side, which faces the collimation lens 4, of the narrowband optical filter 5 is connected to the heat sink 2 at a preset tilt angle;

    a second MPD (which is shown as an MPD 2 in FIG. 5) disposed above the 10 G-DML into which the MPD 1 is integrated; and

    a wavelength locking monitoring circuit 6 connected to the TO pin 3 disposed at one side of the TO base 1, and a wavelength locking control circuit 7 connected to the wavelength locking monitoring circuit 6, where

    a forward emitted light emitted by the 10 G-DML is input to the narrowband optical filter 5 through the collimation lens 4, and a backward emitted light emitted by the 10 G-DML is input to the MPD 1; and the narrowband optical filter 5 reflects, at a preset elevation angle, the forward emitted light to the MPD 2, that is, the MPD 2 receives a reflected light of the narrowband optical filter 5;

    the MPD 1 receives and monitors a third optical power of the backward emitted light, and the MPD 2 receives and monitors a fourth optical power of the reflected light of the narrowband optical filter; and

    the wavelength locking monitoring circuit 6 that receives the third optical power and the fourth optical power by using the TO pin 3 separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the third optical power and the fourth optical power, and sends a comparison result to the wavelength locking control circuit 7, to enable the wavelength locking control circuit 7 to adjust, according to the comparison result and by using the TO pin 3, a temperature of the TEC to perform wavelength alignment, where the wavelength locking factor K0 is a ratio of the third optical power to the fourth optical power or a difference between the third optical power and the fourth optical power.



    [0046] It should be noted that "first", "second", "third", and "fourth" herein are used only for differentiating different monitored optical powers.

    [0047] Preferably, the wavelength locking monitoring circuit 6 that separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the third optical power and the fourth optical power, and sends a comparison result to the wavelength locking control circuit 7 includes:

    calculating a wavelength locking factor K1 based on an average value of measurement values of third optical powers of the first MPD and an average value of measurement values of fourth optical powers of the second MPD, where the average values are acquired when the wavelength locking control circuit 7 adjusts the temperature of the TEC by increasing the temperature of the TEC by preset a degrees Celsius and reducing the temperature of the TEC by preset a degrees Celsius, and determining whether a difference between the wavelength locking factor K1 and a wavelength locking factor K0 that is obtained in advance through calculation exceeds a threshold; if yes, calculating a wavelength locking factor K2 based on an average value of measurement values of third optical powers of the first MPD and an average value of measurement values of fourth optical powers of the second MPD, where the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset b degrees Celsius and reducing the temperature of the TEC by preset b degrees Celsius, and determining whether a difference between the wavelength locking factor K2 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; and if yes, determining that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 G-DML drift, and enabling the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0, where

    preset b degrees Celsius is greater than preset a degrees Celsius.



    [0048] Based on the optical transmitter disclosed in this embodiment of the present invention, a BS is built in the narrowband optical filter 5, and one surface, which is in contact with the heat sink 2, of the narrowband optical filter 5 is machined to be at an oblique angle, and the narrowband optical filter 5 may also be an Etalon FILTER having an obliquely built-in BS; and the 10 G-DML may also be a 10 G-DFB.

    [0049] The optical transmitter disclosed in the Embodiment of the present invention uses a tube core of a 10 G-DML into which an MPD 1 is integrated, and compared with an optical transmitter in Embodiment 1 of the present invention, the MPD 1 disclosed in Embodiment 5 of the present invention only needs to monitor a backlight power of the 10 G-DML, that is an optical power of a backward emitted light, and it does not need to be considered that the backlight power and an optical power of a backward reflected light of a narrowband optical filter complement each other. An MPD 2 disposed outside the 10 G-DML is used to independently monitor a reflected light, which is emitted by the narrowband optical filter that has a tilt angle with a heat sink, of a forward emitted light of the 10 G-DML. The optical transmitter disclosed in Embodiment 5 of the present invention also saves an optical isolator, a beam splitter, or the like in a TO, so that an inner structure of the TO is simple, making it easier to package and machine the TO while reducing a cost.

    [0050] In addition, a wavelength locking monitoring circuit receives the third optical power and the fourth optical power by using a TO pin, separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the detected third optical power and the detected fourth optical power, and sends a comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a TEC to perform wavelength alignment. Wavelength locking control is performed on a wavelength of a 10 G-DML into which the MPD 1 is integrated and the narrowband optical filter by using a novel wavelength monitor loop, so that the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    Embodiment 6



    [0051] Based on an optical transmitter disclosed in the Embodiment of the present invention, based on the optical transmitter, this embodiment of the present invention further correspondingly discloses a wavelength alignment method. The method is based on a schematic structural diagram of an optical transmitter shown in FIG. 5, and mainly includes the following steps:
    Step S202. According to a preset time interval and based on a current standard working point, control a wavelength locking control circuit to adjust a temperature of the TEC to increase preset a degrees Celsius and reduce preset a degrees Celsius, and acquire an average value of measurement values of third optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of measurement values of fourth optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K1.

    [0052] In step S202, increasing preset a degrees Celsius and reducing preset a degrees Celsius refer to a relatively small temperature deviation, that is, during performing of step S202, the wavelength locking control circuit is controlled to perform fine adjustment to increase or reduce the temperature of the TEC by a degrees Celsius, an average value of measurement values of third optical powers that are separately detected by the first MPD after two times of adjustment is acquired, an average value of measurement values of fourth optical powers that are separately detected by the second MPD after the two times of adjustment is acquired, subsequently, a ratio of the average value of the measurement values of the optical powers that are monitored by the first MPD in the two times to the average value of the measurement values of the optical powers that are monitored by the second MPD in the two times is calculated, and the ratio is used as the wavelength locking factor K1.

    [0053] Step S203. Determine whether a difference between the wavelength locking factor K1 and a wavelength locking factor K0 that is obtained in advance through calculation exceeds a threshold; if not, go back to perform step S202; and if yes, perform step S204.

    [0054] Step S204. Based on the current standard working point, control the wavelength locking control circuit to adjust the temperature of the TEC by increasing the temperature of the TEC by preset b degrees Celsius and reducing the temperature of the TEC by preset b degrees Celsius, and acquire an average value of the measurement values of the third optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of measurement values of the fourth optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K2.

    [0055] In step S204, increasing preset b degrees Celsius and reducing preset b degrees Celsius refer to a relatively great temperature deviation, where preset b degrees Celsius is greater than preset a degrees Celsius. During performing of step S202, the wavelength locking control circuit is controlled to perform great adjustment to increase or reduce the temperature of the TEC by b degrees Celsius, based on b degrees Celsius by which the temperature of the TEC is increased or reduced, an average value of measurement values of third optical powers that are separately detected by the first MPD after two times of adjustment is acquired, an average value of measurement values of fourth optical powers that are separately detected by the second MPD after the two times of adjustment is acquired, subsequently, a ratio of the average value of the measurement values of the optical powers that are monitored by the first MPD in the two times to the average value of the measurement values of the optical powers that are monitored by the second MPD in the two times is calculated, and the ratio is used as the wavelength locking factor K2.

    [0056] Step S205. Determine whether a difference between the wavelength locking factor K2 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; if not, go back to perform step S202; and if yes, perform step S206.

    [0057] S206. Determine that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 G-DML drift, and enable the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0.

    [0058] As shown in FIG. 6, during performing of the wavelength alignment method provide in Embodiment 6 of the present invention, an optical power monitored by an MPD 1 is proportional to an optical power of the forward emitted light of the 10 G-DML, and may be used as input of an automatic optical power control loop, an input end of the automatic optical power control loop is connected to the MPD 1 and an MPD2, and the MPD 2 monitors a reflected light of a narrowband optical filter, where an X-axis indicates a value of the temperature of the TEC, and an Y-axis indicates a value of an optical power that corresponds to the temperature of the TEC.

    [0059] During performing of step S206, the enabling the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0 specifically includes:

    [0060] Step S2061. Based on the current standard working point, acquire measurement values of optical powers of the first MPD and the second MPD that are detected after the wavelength locking control circuit adjusts the temperature of the TEC, to calculate a wavelength locking factor K3, and determine whether the wavelength locking factor K3 is within a reference wavelength locking factor range; if yes, perform step S2062 or step S2063; and if the wavelength locking factor K3 is not within the reference wavelength locking factor range, continue to enable the wavelength locking control circuit to adjust the temperature of the TEC, until the wavelength locking factor K3 is within the reference wavelength locking factor range, where
    the reference wavelength locking factor range is [K0-K, K0+K'], and K and K' have a same value or have different values, and are both less than K0.

    [0061] During performing of step S2061, the measurement values of the optical powers of the first MPD and the second MPD that are detected after the temperature of the TEC is adjusted are used to calculate the wavelength locking factor K3, and if the wavelength locking factor K3 is not within the reference wavelength locking factor range being [K0-K, K0+K'], adjustment of the temperature of the TEC is continued, until K3 is within the reference wavelength locking factor range. Specifically, step S2061 is performed to enable K3 to be infinitely close to K0.

    [0062] Step S2062. Control the wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0.

    [0063] When step S2062 is performed, in fact, the wavelength of the 10 G-DML is controlled to be aligned with the wavelength locking factor K3, that is, K3 that is acquired during performing of step S2061 and is infinitely close to K0; and therefore, preferably, it may be considered that the wavelength of the 10 G-DML is controlled to be aligned with the wavelength locking factor K0.

    [0064] Step S2063. When it is determined that the wavelength locking factor K3 within the reference wavelength locking factor range is less than the threshold, set a current temperature of the TEC, where the measurement values of the optical powers of the first MPD and the second MPD are values at a next standard working point, that is, a standard working point when step S202 is performed next time.

    [0065] It should be noted that there is not a particular sequential order for performing step S2062 and step S2063.

    [0066] Moreover, as shown in FIG. 7, before step S202 to step S206 are performed, step S200 and step S201 of obtaining the wavelength locking factor K0 through calculation are first performed as follows. FIG. 6 shows a flowchart of an exemplary wavelength alignment method provided in Embodiment 6 of the present invention.

    [0067] Step S200. The wavelength locking monitoring circuit reads a temperature of the TEC at the current standard working point, a measurement value M3 of a third standard optical power of the first MPD, and a measurement value M4 of a fourth standard optical power of the second MPD, and reads a measurement value M5 of an optical power of the first MPD and a measurement value M6 of an optical power of the second MPD, where the measurement values M5 and M6 are after the temperature of the TEC is adjusted by a preset temperature.

    [0068] During performing of step S200, the measurement value M5 of the optical power of the first MPD and the measurement value M6 of the optical power of the second MPD are read, where the measurement values M5 and M6 are after the temperature of the TEC is adjusted by a preset temperature, where the preset temperature also belongs to a fine adjustment range, that is, may be the preset a degrees Celsius.

    [0069] Step S201. Calculate rates of changes in M3/M4 and M5/M6 with changes in the temperature, and use the rate of change as the wavelength locking factor K0, or use a ratio of M5 to M6 as the wavelength locking factor K0.

    [0070] Based on a novel wavelength monitor loop in an optical transmitter provided in Embodiment 5 of the present invention, and a corresponding wavelength alignment method provided in Embodiment 6 of the present invention, optical powers that are monitored by an MPD 1 and an MPD 2 are combined and input to a wavelength locking monitoring circuit through a TO pin, and subsequently, a temperature of a TEC is adjusted according to the foregoing disclosed wavelength alignment method and according to the optical powers that are detected by the MPD 1 and the MPD 2 to perform wavelength alignment. That is, by using the foregoing novel wavelength monitor loop and the wavelength alignment method that corresponds to the novel wavelength monitor loop, wavelength locking control is performed on a wavelength of a 10 G-DML into which the MPD 1 is integrated and a narrowband optical filter, so that the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    [0071] This embodiment of the present invention further discloses an optical transmitter, where similarly, a 10 G-DML, an MPD 1, an MPD 2, a collimation lens, and a narrowband optical filter are disposed in a TO; therefore, monitoring of an optical power can be achieved, and the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future, which is specifically described as follows.

    Embodiment 7



    [0072] FIG. 8 is an optical transmitter according to Embodiment 7 of the present invention, mainly including:

    a laser transmitter TO base 1, a TEC, and a heat sink 2 that are transverse and are connected sequentially from bottom to top;

    a TO pin 3 whose one side is connected to one end of the TO base 1;

    a first MPD (which is shown as an MPD 1 in FIG. 8), a 10 G-DML, a collimation lens 4, and a narrowband optical filter 5 that are disposed above the heat sink 2, where the MPD 1 is integrated into the 10 G-DML, the collimation lens 4 is located between the 10 G-DML and the narrowband optical filter 5, and one side, which faces the collimation lens 4, of the narrowband optical filter 5 is connected to the heat sink 2 at a preset tilt angle;

    a second MPD (which is shown as an MPD 2 in FIG. 8) that is disposed above the narrowband optical filter 5 and connected to the narrowband optical filter 5; and

    a wavelength locking monitoring circuit 6 connected to the TO pin 3 disposed at one side of the TO base 1, and a wavelength locking control circuit 7 connected to the wavelength locking monitoring circuit 6, where

    a forward emitted light emitted by the 10 G-DML is input to the narrowband optical filter 4 through the collimation lens 5, and a backward emitted light emitted by the 10 G-DML is input to the MPD 1; and the narrowband optical filter 5 reflects a forward transmitted light, which is split from the forward emitted light, to the MPD 2 connected to the narrowband optical filter 5;

    the MPD 1 receives and monitors a fifth optical power of the backward emitted light, and the MPD 2 receives and monitors a sixth optical power of the forward transmitted light; and

    the wavelength locking monitoring circuit 6 that receives the fifth optical power and the sixth optical power by using the TO pin 3 separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the fifth optical power and the sixth optical power, and sends a comparison result to the wavelength locking control circuit 7, to enable the wavelength locking control circuit 7 to adjust, according to the comparison result and by using the TO pin 3, a temperature of the TEC to perform wavelength alignment, where the wavelength locking factor K0 is a ratio of the fifth optical power to the sixth optical power or a difference between the fifth optical power and the sixth optical power.



    [0073] It should be noted that "first", "second", "third", "fourth", "fifth", and "sixth" herein are used only for differentiating different monitored optical powers.

    [0074] Preferably, the wavelength locking monitoring circuit 6 that separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the fifth optical power and the sixth optical power, and sends a comparison result to the wavelength locking control circuit includes:

    the wavelength locking monitoring circuit being configured to: calculate a wavelength locking factor K4 based on an average value of measurement values of fifth optical powers of the first MPD and an average value of measurement values of sixth optical powers of the second MPD, where the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset d degrees Celsius and reducing the temperature of the TEC by preset d degrees Celsius, and determine whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; if yes, calculate a wavelength locking factor K5 based on an average value of measurement values of fifth optical powers of the first MPD and an average value of measurement values of sixth optical powers of the second MPD, where the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and determine whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; and if yes, determine that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 G-DML drift, and enable the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0, where

    preset e degrees Celsius is greater than preset d degrees Celsius.



    [0075] Based on the optical transmitter disclosed in this embodiment of the present invention, a BS is built in the narrowband optical filter 5, and one surface, which is in contact with the heat sink 2, of the narrowband optical filter 5 is machined to be at an oblique angle, and the narrowband optical filter 5 may also be an Etalon FILTER having an obliquely built-in BS; and the 10 G-DML may also be a 10 G-DFB.

    [0076] The optical transmitter disclosed in Embodiment 7 of the present invention also uses a tube core of a 10 G-DML into which an MPD 1 is integrated, and the MPD 1 disclosed in Embodiment 7 of the present invention also only needs to monitor a backlight power of the 10 G-DML, that is an optical power of a backward emitted light, and it does not need to be considered that the backlight power and an optical power of a backward reflected light of a narrowband optical filter complement each other. A difference between Embodiment 7 of the present invention and Embodiment 5 of the present invention lies in that, Embodiment 7 of the present invention uses an MPD 2 that is disposed above a narrowband optical filter and is connected to the narrowband optical filter, to independently monitors a partial optical power, which is emitted by the narrowband optical filter that has a tilt angle with a heat sink, in a forward emitted light of the 10 G-DML, that is, an optical power of a forward transmitted light that is split from the forward emitted light. The optical transmitter disclosed in Embodiment 7 of the present invention also saves an optical isolator, a beam splitter, or the like in a TO, so that an inner structure of the TO is simple, making it easier to package and machine the TO while reducing a cost.

    [0077] In addition, a wavelength locking monitoring circuit receives the fifth optical power and the sixth optical power by using a TO pin, separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the fifth optical power and the sixth optical power, and sends a comparison result to the wavelength locking control circuit, to enable the wavelength locking control circuit to adjust, according to the comparison result and by using the TO pin, a temperature of a TEC to perform wavelength alignment. Wavelength locking control is performed on a wavelength of a 10 G-DML into which the MPD 1 is integrated and the narrowband optical filter by using a novel wavelength monitor loop, so that the optical transmitter disclosed in this embodiment of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    Embodiment 8



    [0078] Based on an optical transmitter disclosed in Embodiment 7 of the present invention, based on the optical transmitter, this embodiment of the present invention further correspondingly discloses a wavelength alignment method. The method is based on a schematic structural diagram of an optical transmitter shown in FIG. 8, and as shown in FIG. 9, the wavelength alignment method mainly includes the following steps:

    Step S301. According to a preset time interval and based on an initial working point, control a wavelength locking control circuit to adjust a temperature of the TEC to increase preset d degrees Celsius and reduce preset d degrees Celsius, and acquire an average value of measurement values of fifth optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of measurement values of sixth optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K4.

    Step S302. Determine whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; if not, go back to perform step S301; and if yes, perform step S303.

    Step S303. Based on the initial working point, control the wavelength locking control circuit to adjust the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and acquire an average value of the measurement values of the fifth optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of the measurement values of the sixth optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K5, where preset e degrees Celsius is greater than preset d degrees Celsius.

    Step S304. Determine whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a threshold; if not, go back to perform step S301; and if yes, perform step S305.

    Step S305. Determine that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 G-DML drift, and enable the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0.



    [0079] During performing of step S305, the enabling the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0 specifically includes:
    Step S3051. Based on the initial working point, acquire the measurement values of the fifth optical power of the first MPD and the sixth optical power of the second MPD to calculate a wavelength locking factor K6, where the fifth optical power and the sixth optical power are detected after the wavelength locking control circuit adjusts the temperature of the TEC, and determine whether the wavelength locking factor K6 is within a reference wavelength locking factor range, if yes, perform step S3052, and if the wavelength locking factor K6 is not within the reference wavelength locking factor range, continue to enable the wavelength locking control circuit to adjust the temperature of the TEC, until the wavelength locking factor K6 is within the reference wavelength locking factor range, where
    the reference wavelength locking factor range is [K0-K, K0+K'], and K and K' have a same value or have different values, and are both less than K0.

    [0080] During performing of step S3051, the measurement values of the fifth optical power of the first MPD and the sixth optical power of the second MPD that are detected after the temperature of the TEC is adjusted are used to calculate the wavelength locking factor K6, and if the wavelength locking factor K6 is not within the reference wavelength locking factor range being [K0-K, K0+K'], adjustment of the temperature of the TEC is continued, until K6 is within the reference wavelength locking factor range. Specifically, step S3051 is performed to enable K6 to be infinitely close to K0.

    [0081] Step S3052. Control the wavelength of the 10 G-DML to be aligned with the wavelength locking factor K0.

    [0082] When step S3052 is performed, in fact, the wavelength of the 10 G-DML is controlled to be aligned with the wavelength locking factor K6, that is, K6 that is acquired during performing of step S3051 and is infinitely close to K0; and therefore, preferably, it may be considered that the wavelength of the 10 G-DML is controlled to be aligned with the wavelength locking factor K0.

    [0083] It should be noted that, the foregoing obtaining a wavelength locking factor K0 through initial calculation is: calculating a wavelength locking factor K0 according to a TEC that has a determined temperature and that is obtained by initializing the 10 G-DFB, and the measurement values of the optical powers of the first MPD and the second MPD.

    [0084] A process of the initializing the 10 G-DML mainly includes:

    Step S401. Test a correspondence between a power P and a drive current I of the tube core of the DML, and set an initial bias current Ib and a modulation current Im of the DML according to the correspondence.

    Step S402. In a case of adding a 10 G-signal, scan the temperature of the TEC, and search for a greatest power value of the 10 G-DML.

    Step S403. Increase the temperature of the TEC according to the greatest power value, and measure a current optical output power, an extinction ratio ER, and an eye pattern;

    Step S404. When the current optical output power is greater than 2 dBm, determine that a corresponding temperature of the TEC is a lower limit initial value of an effective wavelength region of the narrowband optical filter.

    Step S405. When the extinction ratio ER is greater than a preset ratio, and the eye pattern meets a standard mask, determine that the corresponding temperature of the TEC is an upper limit initial value of the effective wavelength region of the narrowband optical filter.



    [0085] The preset ratio mentioned in step S405 is preferably 8.2 dB or 6 dB. The standard mask herein refers to a test template requirement in a communications protocol standard on an eye pattern at a transmit end, and the eye pattern should meet an index of the mask template.

    [0086] Step S406. Within a range formed by the upper limit initial value and the lower limit initial value, measuring whether sensitivity of a boundary point and an intermediate zone of the range is less than preset sensitivity; if yes, perform step S407; and if not, perform step S408.

    [0087] A value of the preset sensitivity mentioned in step S406 is preferably -28 dBm.

    [0088] Step S407. Set a middle point in the range formed by the upper limit initial value and the lower limit initial value as an initial working point, and preliminarily determine that an initial status of the 10 G-DML includes the temperature of the TEC at the initial working point, and the measurement values of the fifth optical power of the first MPD and the sixth optical power of the second MPD.

    [0089] Step S408. Based on the boundary point, narrow the boundary point of the effective wavelength region inwards, until it is found through measurement that sensitivity of a narrowed boundary point and the intermediate zone is less than the preset sensitivity.

    [0090] During performing of the wavelength alignment method disclosed in Embodiment 8 of the present invention, during initialization of a 10 G-DML into which an MPD 1 is integrated, debugging is performed on a temperature of a TEC to set the 10 G-DML to be aligned with an effective wavelength region of a narrowband optical filter. A wavelength locking monitoring circuit combines an optical power, that is monitored by the MPD 1, of a backward emitted light of the 10 G-DML with a partial optical power, which is monitored by an MPD 2 and is received by a narrowband optical filter, in a forward emitted light, that is an optical power of a forward transmitted light. In the wavelength alignment method disclosed in Embodiment 8 of the present invention, the wavelength locking monitoring circuit adjusts, according to the foregoing disclosed wavelength alignment method and according to the optical powers that are detected by the MPD 1 and the MPD 2, the temperature of the TEC to perform wavelength alignment.

    [0091] Based on the optical transmitter disclosed in this embodiment of the present invention, and the wavelength alignment method corresponding to the optical transmitter, this embodiment of the present invention further correspondingly discloses a passive optical network system, which, as shown in FIG. 10, mainly includes: an OLT 11, a beam splitter 12, an ONU 13, and an optical fiber, where
    the optical fiber includes: a feeder optical fiber 41 and a distribution optical fiber 42; and the OLT 11 includes any optical transmitter disclosed in the embodiments of the present invention;
    one end of the feeder optical fiber 41 is connected to the OLT 11, and the other end is connected to the beam splitter 12;
    the beam splitter 12 is connected to the feeder optical fiber 41 to form an optical distribution network ODN; and
    multiple optical network units ONUs 13 are connected to the beam splitter 12 by using the distribution optical fiber 42, and are connected to the OLT 11 (central office) by using the feeder optical fiber 41 and after being aggregated; and the ONUs 13 share the feeder optical fiber 41 in a TDMA manner.

    [0092] To sum up, for an optical transmitter and a wavelength alignment method that corresponds to the optical transmitter, and a passive optical network system having the optical transmitter disposed that are disclosed in the foregoing embodiments of the present invention, a novel wavelength monitor loop is used to achieve wavelength locking control of a wavelength of a 10 G-DML and a narrowband optical filter, so that the optical transmitter disclosed in the embodiments of the present invention can achieve an objective of a high modulation rate with a low cost and low power consumption, where a chirp phenomenon is reduced, thereby enabling the optical transmitter to be applied to a 10 G-PON currently and a higher-rate PON system in the future.

    [0093] The embodiments in this specification are all described in a progressive manner, for same or similar parts in the embodiments, reference may be made to these embodiments, and each embodiment focuses on a difference from other embodiments. The apparatus disclosed in the embodiment is basically similar to the method disclosed in the embodiment, and therefore is described briefly; for related parts, reference may be made to partial descriptions of the method.

    [0094] In combination with the embodiments disclosed in this specification, method or algorithm steps may be implemented by hardware, a software module executed by a processor, or a combination thereof. The software module may be disposed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or a storage medium in any other forms well-known in the art.

    [0095] The foregoing description of the disclosed embodiments enables a person skilled in the art to implement or use the present invention.


    Claims

    1. An optical transmitter, comprising:

    a transmitter optical, TO, base (1), a thermoelectric cooler, TEC, and a heat sink (2) that are transverse and are connected sequentially from bottom to top;

    a first monitor photodiode, MPD, (1), a 10 Gigabits per second-directly modulated laser , 10 Gbps-DML, a collimation lens (4), and a narrowband optical filter (5) that are disposed above the heat sink (2), wherein the first MPD is integrated into the 10 Gbps-DML, the collimation lens (4) is located between the 10 Gbps-DML and the narrowband optical filter (5), and one side, which faces the collimation lens (4), of the narrowband optical filter (5) is connected to the heat sink (23) at a preset oblique tilt angle;

    a second MPD (2) that is disposed above the narrowband optical filter (5) and optically connected to the narrowband optical filter (5); and a wavelength locking monitoring circuit (6) connected to a TO pin (3) disposed at one side of the TO base (1), and a wavelength locking control circuit (7) connected to the wavelength locking monitoring circuit (6), wherein

    a forward emitted light emitted by the 10 Gbps-DML laser is input to the narrowband optical filter (5) through the collimation lens (4), and a backward emitted light emitted by the 10 Gbps-DML is input to the first MPD; and the narrowband optical filter (5) reflects a forward transmitted light, which is split from the forward emitted output light, to the second MPD (2) connected to the narrowband optical filter (5);

    the first MPD receives and monitors a first optical power of the backward emitted light, and the second MPD (2) receives and monitors a second optical power of the forward transmitted light; and

    the wavelength locking monitoring circuit (6) that receives the first optical power and the second optical power by using the TO pin (3) of the TO base (1) separately compares a variation of a wavelength locking factor K0 with a corresponding threshold based on variations of the first optical power and the second optical power, and sends a comparison result to the wavelength locking control circuit (7), to enable the wavelength locking control circuit (7) to adjust, according to the comparison result and by using the TO pin (3), a temperature of the TEC to perform wavelength alignment.


     
    2. The optical transmitter according to claim 1, wherein the wavelength locking monitoring circuit that separately compares the variation of the wavelength locking factor K0 with the corresponding threshold based on variations of the first optical power and the second optical power, and sends the comparison result to the wavelength locking control circuit comprises:

    the wavelength locking monitoring circuit being configured to: calculate a wavelength locking factor K4 based on an average value of measurement values of first optical powers of the first MPD and an average value of measurement values of second optical powers of the second MPD, wherein the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset d degrees Celsius and reducing the temperature of the TEC by preset d degrees Celsius, and determine whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a first threshold; if yes, calculate a wavelength locking factor K5 based on an average value of measurement values of first optical powers of the first MPD and an average value of measurement values of second optical powers of the second MPD, wherein the average values are acquired when the wavelength locking control circuit adjusts the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and determine whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a second threshold; and if yes, determine that wavelengths of the forward emitted light and the backward emitted light that are emitted by the 10 Gbps-DML drift, and enable the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 Gbps-DML to be aligned with the wavelength locking factor K0, wherein

    preset e degrees Celsius is greater than preset d degrees Celsius.


     
    3. A wavelength alignment method, applied to the optical transmitter according to claim 1 or 2, wherein the method comprises:

    according to a preset time interval and based on an initial working point, controlling a wavelength locking control circuit to adjust a temperature of the TEC to increase preset d degrees Celsius and reduce preset d degrees Celsius, and acquiring an average value of measurement values of first optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of measurement values of second optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K4 (S301);

    determining whether a difference between the wavelength locking factor K4 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a first threshold, and if not, going back to the step of calculating a wavelength locking factor K4 according to a preset time interval and based on the initial working point (S302); and

    if yes, based on the initial working point, controlling the wavelength locking control circuit to adjust the temperature of the TEC by increasing the temperature of the TEC by preset e degrees Celsius and reducing the temperature of the TEC by preset e degrees Celsius, and acquiring an average value of the measurement values of the first optical powers, which are obtained through two times of monitoring, of the first MPD, and an average value of the measurement values of the second optical powers, which are obtained through two times of monitoring, of the second MPD, to calculate a wavelength locking factor K5, wherein preset e degrees Celsius is greater than preset d degrees Celsius (S303);

    determining whether a difference between the wavelength locking factor K5 and a wavelength locking factor K0 that is obtained through initial calculation exceeds a second threshold, and if not, going back to the step of calculating a wavelength locking factor K4 according to a preset time interval and based on the initial working point (S304); and

    if yes, determining that wavelengths of a forward emitted light and a backward emitted light that are emitted by a 10 Gbps-DML drift, and enabling the wavelength locking control circuit to send, by using the TO pin, an instruction for adjusting the temperature of the TEC, and control a wavelength of the 10 Gbps-DML to be aligned with the wavelength locking factor K0 (S305).


     
    4. The method according to claim 3, wherein the obtaining the wavelength locking factor K0 through initial calculation comprises:

    calculating a wavelength locking factor K0 according to a TEC that has a determined temperature and that is obtained by initializing the 10 Gbps-DML, and the measurement values of the first optical power of the first MPD and the second optical power of the second MPD; and

    the initializing the 10 Gbps-DML comprises:

    testing a correspondence between a power P of a tube core of the DML and a drive current I, and setting an initial bias current Ib and a modulation current Im of the DML according to the correspondence;

    in a case of adding a 10 Gbps-signal, scanning the temperature of the TEC, and searching for a greatest power value of the 10 Gbps-DML;

    increasing the temperature of the TEC according to the greatest power value, and measuring a current optical output power, an extinction ratio ER, and an eye pattern;

    when the current optical output power is greater than 2 dBm, determining that a corresponding temperature of the TEC is a lower limit initial value of an effective wavelength region of the narrowband optical filter;

    when the extinction ratio ER is greater than a preset ratio, and the eye pattern meets a standard mask, determining that the corresponding temperature of the TEC is an upper limit initial value of the effective wavelength region of the narrowband optical filter; and

    within a range formed by the upper limit initial value and the lower limit initial value, measuring whether sensitivity of a boundary point and an intermediate zone of the range is less than preset sensitivity;

    if yes, setting a middle point in the range formed by the upper limit initial value and the lower limit initial value as an initial working point, and preliminarily determining that an initial status of the 10 Gbps-DML comprises the temperature of the TEC at the initial working point, and the measurement values of the first optical power of the first MPD and the second optical power of the second MPD; and

    if not, based on the boundary point, narrowing the boundary point of the effective wavelength region inwards, until it is found through measurement that sensitivity of a narrowed boundary point and the intermediate zone is less than the preset sensitivity.


     


    Ansprüche

    1. Optischer Sender, umfassend:

    eine sendeoptische, TO, Basis (1), einen thermoelektrischen Kühler, TEC, und eine Wärmesenke (2), die quer stehen und sequenziell von unten nach oben verbunden sind; eine erste Überwachungsphotodiode, MPD, (1), einen 10 Gigabit-pro-Sekunde direktmodulierten Laser, 10 Gbps-DML, eine Kollimationslinse (4) und einen optischen Schmalbandfilter (5), die über der Wärmesenke (2) angeordnet sind, wobei die erste MPD ist in den 10 Gbps-DML integriert ist, die Kollimationslinse (4) sich zwischen dem 10 Gbps-DML und dem optischen Schmalbandfilter (5) befindet, und eine Seite, des optischen Schmalbandfilters (5), die zu der Kollimationslinse (4) zeigt, mit der Wärmesenke (23) in einem voreingestellten schrägen Kippwinkel verbunden ist;

    eine zweite MPD (2), die über dem optischen Schmalbandfilter (5) angeordnet und optisch mit dem optischen Schmalbandfilter (5) verbunden ist; und

    einen Wellenlängensperrüberwachungskreis (6), der mit einem TO-Stift (3) verbunden ist, der auf einer Seite der TO-Basis (1) angeordnet ist, und einen Wellenlängensperrsteuerkreis (7), der mit dem Wellenlängensperrüberwachungskreis (6) verbunden ist, wobei

    ein vorwärts ausgegebenes Licht, das durch den 10 Gbps-DML-Laser ausgegeben wird, in den optischen Schmalbandfilter (5) durch die Kollimationslinse (4) eingegeben wird und ein rückwärts ausgegebenes Licht, das durch den 10 Gbps-DML ausgegebenen wird, in die erste MPD eingegeben wird; und der optische Schmalbandfilter (5) ein vorwärts übertragenes Licht, das von dem vorwärts ausgegebenen Ausgabelicht getrennt ist, an die MPD (2) reflektiert, die mit dem optischen Schmalbandfilter (5) verbunden ist;

    die erste MPD eine erste optische Leistung des rückwärts ausgegeben Lichts empfängt und überwacht und die zweite MPD (2) eine zweite optische Leistung des vorwärts übertragenen Lichts empfängt und überwacht; und

    der Wellenlängensperrüberwachungskreis (6), der die erste optische Leistung und die zweite optische Leistung durch Verwendung des TO-Stifts (3) der TO-Basis (1) empfängt, separat eine Variation eines Wellenlängensperrfaktors K0 mit einem entsprechenden Grenzwert basierend auf Variationen der ersten optischen Leistung und der zweiten optischen Leistung vergleicht, und ein Vergleichsergebnis an den Wellenlängensperrsteuerkreis (7), sendet, damit der Wellenlängensperrsteuerkreis (7) dem Vergleichsergebnis entsprechend und unter Verwendung des TO Stifts (3) eine Temperatur des TEC anpassen kann, um die Wellenlängenausrichtung auszuführen.


     
    2. Optischer Sender nach Anspruch 1, wobei der Wellenlängensperrüberwachungskreis, der die Variation des Wellenlängensperrfaktors K0 mit dem entsprechenden Grenzwert auf Grundlage von Variationen der ersten optischen Leistung und der zweiten optischen Leistung vergleicht und das Vergleichsergebnis an den Wellenlängensperrsteuerkreis sendet, umfasst:

    Konfiguration des Wellenlängensperrüberwachungskreises, um: einen Wellenlängensperrfaktor K4 basierend auf einem Durchschnittswert der Messwerte der ersten optischen Leistung der ersten MPD und eines Durchschnittswerts der Messwerte der zweiten optischen Leistungen der zweiten MPD zu berechnen, wobei die Durchschnittswerte erfasst werden, wenn der Wellenlängensperrsteuerkreis die Temperatur des TEC um voreingestellte d Grad Celsius erhöht und die Temperatur des TEC durch voreingestellte d Grad Celsius verringert, und zu bestimmen, ob eine Differenz zwischen dem Wellenlängensperrfaktor K4 und einem Wellenlängensperrfaktor K0, die durch die anfängliche Berechnung erreicht wird, einen ersten Grenzwert überschreitet; wenn ja, Berechnung eines Wellenlängensperrfaktors K5 basierend auf einem Durchschnittswert von Messwerten erster optischer Leistungen der ersten MPD und eines Durchschnittswerts der Messwerte zweiter optischer Leistungen der zweiten MPD, wobei die Durchschnittswerte erfasst werden, wenn der Wellenlängensperrsteuerkreis die Temperatur des TEC durch Erhöhen der Temperatur des TEC um voreingestellte e Grad Celsius und Verringern der Temperatur des TEC um voreingestellte e Grad Celsius anpasst, und Bestimmung, ob eine Differenz zwischen dem Wellenlängensperrfaktor K5 und einem Wellenlängensperrfaktor K0, der durch anfängliche Berechnung beschafft wird, eine zweite Grenze übersteigt; und wenn ja, Bestimmung, dass Wellenlängen des vorwärts abgegebenen Lichts und des rückwärts abgegebenen Lichts, die durch den 10 Gbps-DML-Drift abgegeben werden, und den Wellenlängensperrsteuerkreis in die Lage versetzen, durch Verwendung des TO Stifts eine Anweisung für die Anpassung der Temperatur des TEC zu senden und eine Wellenlänge des 10 Gbps-DML, die an dem Wellenlängensperrfaktor K0 ausgerichtet werden soll, zu steuern, wobei

    voreingestellte e Grad Celsius höher als voreingestellte d Grad Celsius sind.


     
    3. Wellenlängenausrichtverfahren, angewendet auf den optischen Transmitter nach Anspruch oder 2, wobei das Verfahren umfasst:

    nach einem voreingestellten Zeitraum und basierend auf einem anfänglichen Arbeitspunkt, Steuerung eines Wellenlängensperrsteuerkreises zur Einstellung einer Temperatur des TEC zum Erhöhen der voreingestellten d Grad Celsius und Verringern der voreingestellten d Grad Celsius, und Beschaffung eines Durchschnittswerts der Messwerte erster optischer Leistungen, die durch zwei Überwachungszeiten der ersten MPD beschafft werden, und einen Durchschnittswert von Messwerten zweiter optischer Leistungen, die durch zwei Zeiten der Überwachung der zweiten MPD beschafft werden, um einen Wellenlängensperrfaktor K4 (S301) zu berechnen;

    Bestimmung, ob eine Differenz zwischen dem Wellenlängensperrfaktor K4 und einem Wellenlängensperrfaktor K0, der durch anfängliche Berechnung beschafft wird, einen ersten Grenzwert überschreitet, und wenn nicht, zurückgehen zum Schritt der Berechnung eines Wellenlängensperrfaktors K4 nach einem voreingestellten Zeitintervall und basierend auf dem anfänglichen Arbeitspunkt (S302); und

    wenn ja, basierend auf dem anfänglichen Arbeitspunkt, Steuerung des Wellenlängensperrsteuerkreises zur Einstellung der Temperatur des TEC durch Erhöhen der Temperatur des TEC um die voreingestellten e Grad Celsius und Verringern der Temperatur des TEC um die voreingestellten e Grad Celsius, und Beschaffung eines Durchschnittswerts der Messwerte der ersten optischen Leistungen, die durch zwei Überwachungszeiten der ersten MPD beschafft werden, und einen Durchschnittswert der Messwerte der zweiten optischen Leistungen, die durch zwei Zeiten der Überwachung der zweiten MPD zur Berechnung eines Wellenlängensperrfaktors K5 beschafft werden, wobei die voreingestellten e Grad Celsius höher als voreingestellte d Grad Celsius (S303) sind;

    Bestimmung, ob eine Differenz zwischen dem Wellenlängensperrfaktor K5 und einem Wellenlängensperrfaktor K0, der durch anfängliche Berechnung beschafft wird, einen zweiten Grenzwert überschreitet, und wenn nicht, zurückgehen zum Schritt der Berechnung eines Wellenlängensperrfaktors K4 nach einem voreingestellten Zeitintervall und basierend auf dem anfänglichen Arbeitspunkt (S304); und

    wenn ja, Bestimmung, dass Wellenlängen eines vorwärts abgegebenen Lichts und eines rückwärts abgegebenen Lichts, die durch einen 10 Gbps-DML-Drift ausgegeben werden, und in den Wellenlängensperrsteuerkreis in die Lage versetzen zum Senden einer Anweisungen zur Anpassung der Temperatur des TEC und zur Steuerung einer Wellenlänge des 10 Gbps-DML, die an dem Wellenlängensperrfaktor K0 (S305) ausgerichtet werden soll, unter Verwendung des TO-Stifts.


     
    4. Verfahren nach Anspruch 3, wobei die Beschaffung des Wellenlängensperrfaktors K0 durch die anfängliche Berechnung umfasst:

    Berechnung eines Wellenlängensperrfaktors K0 nach einem TEC, der eine bestimmte Temperatur aufweist und durch Initialisierung des 10 Gbps-DML beschafft wird, und die Messwerte der ersten optischen Leistung der ersten MPD und der zweiten optischen Leistung der zweiten MPD; und

    die Initialisierung des 10 Gbps-DML umfasst:

    Prüfung einer Übereinstimmung zwischen einer Leistung P eines Rohrkerns des DML und eines Antriebsstroms I, und Einstellung eines anfänglichen Vorbeaufschlagungsstroms Ib und eines Modulierungsstroms Im des DML der Übereinstimmung entsprechend;

    bei Hinzufügen eines 10 Gbps-Signals, Scannen der Temperatur des TEC und Suche nach dem höchsten Leistungswert des 10 Gbps-DML;

    Erhöhung der Temperatur des TEC nach dem Wert größter Leistung und Messung einer aktuellen optischen Ausgabeleistung, eines Extinktionsverhältnisses ER und eines Augenmusters;

    wenn die aktuelle optische Ausgabeleistung größer als 2 dBm ist, Bestimmung, dass eine entsprechende Temperatur des TEC ein anfänglicher Wert eines unteren Grenzwerts einer effektiven Wellenlängenregion des optischen Schmalbandfilters ist;

    wenn das Extinktionsverhältnis ER größer als ein voreingestelltes Verhältnis ist und das Augenmuster eine Standardmaske trifft, Bestimmung, dass die entsprechende Temperatur des TEC einen Anfangswert des oberen Grenzwerts der effektiven Wellenlängenregion des optischen Schmalbandfilters ist; und

    innerhalb eines Bereichs, der durch den Anfangswert des oberen Grenzwerts und den Anfangswert des unteren Grenzwerts gebildet wird, Messung, ob die Empfindlichkeit eines Grenzpunkts und einer Zwischenzone des Bereichs geringer ist, als die voreingestellte Empfindlichkeit;

    wenn ja, Einstellung eines Mittelpunkts in dem Bereich, der durch den Anfangswert des oberen Grenzwerts und den Anfangswert des unteren Grenzwerts als anfänglicher Arbeitspunkt gebildet ist, und vorläufige Bestimmung, dass ein anfänglicher Status des 10 Gbps-DML die Temperatur des TEC an dem anfänglichen Arbeitspunkt und die Messwerte der ersten optischen Leistung der ersten MPD und der zweiten optischen Leistung der zweiten MPD umfasst; und

    wenn nicht, basierend auf dem Grenzpunkt, Verengung des Grenzpunkts der effektiven Wellenlängenregion nach innen, bis durch Messung festgestellt wird, dass die Empfindlichkeit eines verengten Grenzpunkts und der Zwischenzone geringer als die voreingestellte Empfindlichkeit ist.


     


    Revendications

    1. Émetteur optique, comprenant :
    une base d'optique d'émetteur, notée TO, (1), un refroidisseur thermoélectrique, noté TEC, et un dissipateur thermique (2) transversaux et reliés séquentiellement de bas en haut :

    une première photodiode de contrôle, notée MPD, (1), un laser à modulation directe de 10 gigabits par seconde, noté DML 10 Gbps, une lentille de collimation (4) et un filtre optique à bande étroite (5) placés au-dessus du dissipateur thermique (2), la première MPD étant intégrée dans le DML 10 Gbps, la lentille de collimation (4) étant située entre le DML 10 Gbps et le filtre optique à bande étroite (5) et un côté, en regard de la lentille de collimation (4) du filtre optique à bande étroite (5), étant relié au dissipateur thermique (23) en formant un angle d'inclinaison oblique préétabli ;

    une deuxième MPD (2) placée au-dessus du filtre optique à bande étroite (5) et reliée optiquement au filtre optique à bande étroite (5) ; et

    un circuit de contrôle de verrouillage en longueur d'onde (6) relié à une broche de TO (3) placée d'un côté de la base de TO (1) et un circuit de commande de verrouillage en longueur d'onde (7) relié au circuit de contrôle de verrouillage en longueur d'onde (6), une lumière émise vers l'avant par le laser DML 10 Gbps étant appliquée à l'entrée du filtre optique à bande étroite (5) au travers de la lentille de collimation (4) et une lumière émise vers l'arrière émise par le DML 10 Gbps étant appliquée à l'entrée de la première MPD ; et le filtre optique à bande étroite (5) réfléchissant une lumière transmise vers l'avant, séparée de la lumière de sortie émise vers l'avant, vers la deuxième MPD (2) reliée au filtre optique à bande étroite (5) ;

    la première MPD recevant et contrôlant une première puissance optique de la lumière émise vers l'arrière, et la deuxième MPD (2) recevant et contrôlant une deuxième puissance optique de la lumière transmise vers l'avant ; et

    le circuit de contrôle de verrouillage en longueur d'onde (6) qui reçoit la première puissance optique et la deuxième puissance optique au moyen de la broche de TO (3) de la base de TO (1) comparant séparément une variation d'un facteur de verrouillage en longueur d'onde K0 à un seuil correspondant sur la base de variations de la première puissance optique et de la deuxième puissance optique, et envoyant un résultat de comparaison au circuit de commande de verrouillage en longueur d'onde (7) afin de permettre au circuit de commande de verrouillage en longueur d'onde (7) d'ajuster, selon le résultat de comparaison et au moyen de la broche de TO (3), une température du TEC dans le but d'effectuer une alignement de longueur d'onde.


     
    2. Émetteur optique selon la revendication 1, dans lequel le circuit de contrôle de verrouillage en longueur d'onde qui compare séparément la variation du facteur de verrouillage en longueur d'onde K0 au seuil correspondant sur la base de variations de la première puissance optique et de la deuxième puissance optique, et envoie le résultat de comparaison au circuit de commande de verrouillage en longueur d'onde comprend :
    le circuit de contrôle de verrouillage en longueur d'onde qui est configuré pour :

    calculer un facteur de verrouillage en longueur d'onde K4 sur la base d'une valeur moyenne de valeurs de mesure de premières puissances optiques de la première MPD et d'une valeur moyenne de valeurs de mesure de deuxièmes puissances optiques de la deuxième MPD, les valeurs moyennes étant acquises lorsque le circuit de commande de verrouillage en longueur d'onde ajuste la température du TEC en augmentant la température du TEC de d degrés Celsius préétablis et en réduisant la température du TEC de d degrés Celsius préétablis, et déterminer si une différence entre le facteur de verrouillage en longueur d'onde K4 et un facteur de verrouillage en longueur d'onde K0 obtenu par calcul initial dépasse ou non un premier seuil ; dans l'affirmative, calculer un facteur de verrouillage en longueur d'onde K5 sur la base d'une valeur moyenne de valeurs de mesure de premières puissances optiques de la première MPD et d'une valeur moyenne de valeurs de mesure de deuxièmes puissances optiques de la deuxième MPD, les valeurs moyennes étant acquises lorsque le circuit de commande de verrouillage en longueur d'onde ajuste la température du TEC en augmentant la température du TEC de e degrés Celsius préétablis et en réduisant la température du TEC de e degrés Celsius préétablis, et déterminer si une différence entre le facteur de verrouillage en longueur d'onde K5 et un facteur de verrouillage en longueur d'onde K0 obtenu par calcul initial dépasse ou non un deuxième seuil ; et, dans l'affirmative, déterminer que des longueurs d'onde de la lumière émise vers l'avant et de la lumière émise vers l'arrière émises par le DML 10 Gbps connaissent une dérive, et habiliter le circuit de commande de verrouillage en longueur d'onde à envoyer, au moyen de la broche de TO, une instruction d'ajustement de la température du TEC et commander une longueur d'onde du DML 10 Gbps pour l'aligner avec le facteur de verrouillage en longueur d'onde K0,

    les e degrés Celsius préétablis étant supérieurs aux d degrés Celsius préétablis.


     
    3. Procédé d'alignement de longueur d'onde, appliqué à l'émetteur optique selon la revendication ou 2, lequel procédé comprend :

    selon une intervalle de temps préétabli et sur la base d'un point de fonctionnement initial, la commande faite à un circuit de commande de verrouillage en longueur d'onde d'ajuster une température du TEC pour l'augmenter de d degrés Celsius préétablis et la réduire de d degrés Celsius préétablis, et l'acquisition d'une valeur moyenne de valeurs de mesure de premières puissances optiques, obtenues par un double contrôle, de la première MPD, et d'une valeur moyenne de valeurs de mesure de deuxièmes puissances optiques, obtenues par un double contrôle, de la deuxième MPD, pour calculer un facteur de verrouillage en longueur d'onde K4 (S301) ;

    la détermination si une différence entre le facteur de verrouillage en longueur d'onde K4 et un facteur de verrouillage en longueur d'onde K0 obtenu par calcul initial dépasse ou non un premier seuil et, dans la négative, le retour à l'étape de calcul d'un facteur de verrouillage en longueur d'onde K4 selon un intervalle de temps préétabli et sur la base du point de fonctionnement initial (S302) ; et

    dans l'affirmative, sur la base du point de fonctionnement initial, la commande faite au circuit de commande de verrouillage en longueur d'onde d'ajuster la température du TEC en augmentant la température du TEC de e degrés Celsius préétablis et en réduisant la température du TEC de e degrés Celsius, et l'acquisition d'une valeur moyenne des valeurs de mesure des premières puissances optiques, obtenues par un double contrôle, de la première MPD, et d'une valeur moyenne des valeurs de mesure des deuxièmes puissances optiques, obtenues par un double contrôle, de la deuxième MPD, pour calculer un facteur de verrouillage en longueur d'onde K5, les e degrés Celsius préétablis étant supérieurs aux d degrés Celsius préétablis (S303) ;

    la détermination si une différence entre le facteur de verrouillage en longueur d'onde K5 et un facteur de verrouillage en longueur d'onde K0 obtenu par calcul initial dépasse ou non un deuxième seuil et, dans la négative, le retour à l'étape de calcul d'un facteur de verrouillage en longueur d'onde K4 selon un intervalle de temps préétabli et sur la base du point de fonctionnement initial (S304) ; et

    dans l'affirmative, la détermination que des longueurs d'onde d'une lumière émise vers l'avant et d'une lumière émise vers l'arrière émises par un DML 10 Gbps connaissent une dérive, et l'habilitation du circuit de commande de verrouillage en longueur d'onde à envoyer, au moyen de la broche de TO, une instruction d'ajustement de la température du TEC et commander une longueur d'onde du DML 10 Gbps pour l'aligner avec le facteur de verrouillage en longueur d'onde K0 (S305).


     
    4. Procédé selon la revendication 3, dans lequel l'obtention du facteur de verrouillage en longueur d'onde K0 par calcul initial comprend :

    le calcul d'un facteur de verrouillage en longueur d'onde K0 selon un TEC présentant une température déterminée et obtenu par initialisation du DML 10 Gbps et les valeurs de mesure de la première puissance optique de la première MPD et de la deuxième puissance optique de la deuxième MPD ; et

    l'initialisation du DML 10 Gbps comprenant :

    le test d'une correspondance entre une puissance P d'un tube coeur du DML et un courant d'attaque I, et l'établissement d'un courant de polarisation initial Ib et d'un courant de modulation Im du DML selon la correspondance ;

    suite à l'ajout d'un signal 10 Gbps, le balayage de la température du TEC, et la recherche d'une valeur de puissance maximale du DML 10 Gbps ;

    l'augmentation de la température du TEC selon la valeur de puissance maximale, et la mesure d'une puissance optique de sortie actuelle, d'un rapport d'extinction, noté ER, et d'un diagramme en oeil ;

    lorsque la puissance optique de sortie actuelle est supérieure à 2 dBm, la détermination qu'une température correspondante du TEC constitue une valeur initiale limite inférieure d'un domaine de longueurs d'onde efficace du filtre optique à bande étroite ;

    lorsque le rapport d'extinction ER est supérieur à un rapport préétabli et que le diagramme en oeil correspond à un masque standard, la détermination que la température correspondante du TEC constitue une valeur initiale limite supérieure du domaine de longueurs d'onde efficace du filtre optique à bande étroite ; et

    au sein d'une plage formée par la valeur initiale limite supérieure et la valeur initiale limite inférieure, la mesure visant à déterminer si la sensibilité d'un point de démarcation et d'une zone intermédiaire de la plage est inférieure à une sensibilité préétablie ;

    dans l'affirmative, l'établissement, comme point de fonctionnement initial, d'un point milieu dans la plage formée par la valeur initiale limite supérieure et la valeur initiale limite inférieure, et la détermination préliminaire qu'un état initial du DML 10 Gbps comprend la température du TEC au point de fonctionnement initial et les valeurs de mesure de la première puissance optique de la première MPD et de la deuxième puissance optique de la deuxième MPD ; et

    dans la négative, sur la base du point de démarcation, le rétrécissement rentrant du point de démarcation du domaine de longueurs d'onde efficace jusqu'à ce qu'il soit établi, par la mesure, qu'une sensibilité d'un point de démarcation rétréci et de la zone intermédiaire est inférieure à la sensibilité préétablie.


     




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    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description