Patent ID: 7989754
Filing Date: 2011-08-02
Classification: H04B

Abstract:
1. An optical circuit comprising at least one optical device which inputs one of a first signal light and a second signal light and outputs the other, further comprising; a first photodetector for converting the first signal light to a first detection signal, wherein the first photodetector has a first conversion efficiency; a second photodetector for converting the second signal light to a second detection signal, wherein the second photodetector has a second conversion efficiency; a converter provided for each of the first and second photodetectors, for converting a corresponding detection signal to a monitored signal; and a controller controlling such that the first detection signal is connected to a non-corresponding converter and the second detection signal is connected to the interruption, calculating a first signal value of the first detection signal from the first conversion efficiency and a previously measured level of the first signal light; calculating an imaginary light level of the output signal light from the first signal value calculated and the second conversion efficiency, wherein the imaginary light level of the second signal light is a light level of the second signal light to be input to the second photodetector when the second detection signal exhibits the first signal value calculated; and calculating correlation between the imaginary light level of the second signal light and a monitored signal obtained by the non-corresponding converter inputting the first signal value calculated.