(19)
(11) EP 1 760 520 A8

(12) CORRECTED EUROPEAN PATENT APPLICATION
Note: Bibliography reflects the latest situation

(15) Correction information:
Corrected version no 1 (W1 A2)

(48) Corrigendum issued on:
06.06.2007 Bulletin 2007/23

(43) Date of publication:
07.03.2007 Bulletin 2007/10

(21) Application number: 05025631.2

(22) Date of filing: 24.11.2005
(51) International Patent Classification (IPC): 
G02F 1/225(2006.01)
H04L 27/20(2006.01)
H04B 10/155(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR MK YU

(30) Priority: 31.08.2005 JP 2005252172

(71) Applicant: FUJITSU LIMITED
Kawasaki-shi, Kanagawa 211-8588 (JP)

(72) Inventors:
  • Nakashima, Hisao c/o FUJITSU LIMITED
    Kawasaki-shi Kanagawa 211-8588 (JP)
  • Hoshida, Takeshi c/o FUJITSU LIMITED
    Kawasaki-shi Kanagawa 211-8588 (JP)

(74) Representative: Hoffmann, Klaus 
Hoffmann - Eitle Patent- und Rechtsanwälte Arabellastrasse 4
D-81925 München
D-81925 München (DE)

   


(54) Differential quadrature phase-shift modulator and method for setting driving voltage thereof


(57) The present invention is directed toward a method for setting a driving voltage of a differential quadrature phase-shift modulator, this method making signal quality superior in response to an individual difference in extinction ratio due to variations in manufacture of a device. To this end, signal quality of differential quadrature phase-shift modulated light output from a differential quadrature phase-shift modulator is acquired. An average amplitude of a first or second driving voltage signal is adjusted according to the signal quality of the thus-acquired differential quadrature phase-shift modulated light.