Patent ID: 7016609

Claim:
A receiver transponder used in an optical add/drop node, the receiver transponder comprising: a plurality of optoelectric converters configured to convert received optical signals to electric signals, a first one of the optoelectric converters being connected to an optical fiber carrying light signals from a first direction, a second one of the optoelectric converters being connected to another optical fiber carrying light signals from a second direction opposite the first direction, each optoelectric converter generating an output signal indicative of power of the received optical signals; an electronic switch being coupled to the plurality of optoelectric converters and having a plurality of input terminals, a signal output terminal, and a control input terminal, each of the first and second optoelectric converters having output terminals connected to the input terminals of the electronic switch, the control input terminal receiving a signal to control the electronic switch to select one of the input terminals from which one of the electric signals is switched to the control signal responsive to the output signals indicative of the power of the received optical signals output terminal; and a circuit connected to the output terminal of the electronic switch that adjusts the signal output from the electronic switch to a predetermined power.