Patent ID: 9531479
Filing Date: 2016-12-27
CPC Classification: H04B

Claim Text:
1. A method of monitoring an output wavelength of an optical signal by converting photocurrents generated by two light receiving elements which receive the optical signal into digital signals corresponding to the respective photocurrents, the method comprising: individually causing the respective photocurrents to flow into a resistance element and acquiring voltages generated in the resistance element; providing the acquired voltages as input to an operational amplifier and converting output from the operational amplifier to obtain first and second digital signals; causing the respective photocurrents to flow into the resistance element at the same time and acquiring a voltage generated in the resistance element; providing the acquired voltage as input to the operational amplifier and converting output from the operational amplifier to obtain a third digital signal; and acquiring a corrected digital signal by subtracting the second digital signal from the third digital signal and another corrected digital signal by subtracting the first digital signal from the third digital signal.