|
(11) | EP 1 161 115 A8 |
| (12) | CORRECTED EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Optical switch with power equalization |
| (57) An optical intensity control system for use with an optical switch providing individual
signal paths between input and output ports. The system has a optical splitters connectable
to output multiplexers of the switch and also has variable optical intensity controllers
(VOICs) for insertion into the individual signal paths. The VOICs individually control
the intensity of optical signals present in the signal paths in accordance with intensity
control signals. An equalizer is connected to the splitters and to the VOICs, for
producing an estimate of the optical power of each individual switched optical signal
and generating the intensity control signals. The equalizer is adapted to controllably
isolate individual switched optical signals. In this way, individual and independent
control of the power on each optical channel is provided, wavelength-dependent losses
introduced by all the devices in the switch including the WDM devices at the output
of the switch are accounted for and one optical coupler is required for each output
optical fiber. Coarse equalization may be provided for each multiplexed optical signal
either at the switch input or output, permitting a reduction in the dynamic range
over which the VOICs inside the switch are required to operate. |