Patent ID: 6771905
Filing Date: 2004-08-03
Classification: H04J,H04Q

Abstract:
An optical transmission system comprising:at least one optical transmitter configured to transmit at least one optical signal channel via an optical signal along an optical path; at least one optical receiver configured to receive at least one optical signal channel from said optical path; and, an optical switching device disposed along said optical path including a demultiplexer configured to demultiplex the optical signal provided to an input port a plurality of signal groups including at least one signal channel, a switch element configurable to pass or prevent the passage of at least one of the signal groups and variably control the optical power of the signal groups passing through said switch element, and a multiplexer configured to multiplex the signal groups passed by said switch element into an output signal through an output port in optical communication with said optical receiver, wherein said optical switching device imparts a substantially uniform optical loss across the at least one optical signal channels; an optical amplifier disposed along said optical path including an optical amplifying medium having an input and an output and configured to amplify optical signals passing through said amplifying medium when said amplifying medium is supplied with power; a power source configured to supply power to said amplifying medium, wherein the power supplied by said power source is controlled to maintain a constant output power for each signal channel in the optical signals after passing through said amplifying medium, an input power monitor configured to monitor optical signal power proximate said input of said amplifier; an output power monitor configured to monitor optical signal power proximate said output of said amplifier; a comparator configured to vary the power supplied by said power source based on the optical signal power at said amplifier input and output and a gain set point; and, central processor configured to vary the gain set point of the comparator based on the number of signal channels and the optical signal power at said input to said amplifier.