| 摘要 |
PROBLEM TO BE SOLVED: To accurately monitor the power of a light signal about a signal spectrum without being influenced by a noise spectrum by branching a light signal into 1st and 2nd beams, making them pass through 1st and 2nd light pass band filters having different passbands, after that, converting it into an electric signal and calculating the power of a light signal. SOLUTION: A light signal OS that has a signal spectrum SS1 which is superimposed on a noise spectrum NSI is branched into beams B1 and B2 in 1:1 by an optical coupler 2, and they are made into beams B3 and B4 by optical band path filters 4 and 6 which have passbands PB1 and PB2. Photodetectors 8 and 10 convert the beams B3 and B4 into electric signals S1 and S2 which have levels that correspond to the mean power of the beams B3 and B4. An arithmetic unit 12 performs an operation that is preliminarily defined based on the signals S1 and S2. This makes it possible to calculate the power of the signal OS about the spectrum SSI. |
