Method of monitoring wavelength of optical signal output from light emitting element and optical signal monitoring circuit

摘要

An optical signal monitor circuit includes a PD which directly detects an optical signal and converts the optical signal into a photocurrent, and another PD which detects the optical signal and converts the optical signal into a photocurrent. A resistance element converts the photocurrents into voltages for input to an operational amplifier which outputs voltages based on the voltages generated by the resistance element. A switching control circuit switches a connection between the PDs and the resistance element, and a calculation circuit acquires the output of the operational amplifier converted to digital signals such that the switching control circuit controls switching to cause the two photocurrents to flow into the resistance element at individual timings and to cause the two photocurrents to flow into the resistance element at the same timing, and the calculation circuit calculates a corrected digital signal by subtracting with the obtained digital signals.

主权项

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.