Optical transmitter and bias control method of optical modulator

摘要

An optical transmitter includes: a drive signal generator configured to generate a drive signal from input data; an optical modulator configured to generate an optical signal corresponding to the drive signal; a superimposer configured to superimpose a first reference signal on the drive signal and superimpose a second reference signal on a bias voltage of the optical modulator; a detector configured to detect the first reference signal and the second reference signal included in the optical signal, and generate a first monitor signal indicating intensity and a phase of the detected first reference signal and a second monitor signal indicating intensity and a phase of the detected second reference signal; and a controller configured to control the bias voltage of the optical modulator in a control scheme determined based on the first monitor signal and the second monitor signal.

主权项

1. An optical transmitter comprising:
a drive signal generator configured to generate a drive signal from input data; an optical modulator configured to generate an optical signal corresponding to the drive signal, intensity of output light of the optical modulator periodically changing with respect to an applied voltage; a reference signal generator configured to generate a first reference signal of a first frequency and a second reference signal of a second frequency, the first frequency and the second frequency being different from each other; a superimposer configured to superimpose the first reference signal on the drive signal and superimpose the second reference signal on a bias voltage of the optical modulator; a converter configured to convert the optical signal into an electric signal; a detector configured to detect an intensity and a phase of the first reference signal included in the optical signal from the electric signal with a synchronous detection using the first reference signal generated by the reference signal generator and an intensity and a phase of the second reference signal included in the optical signal from the electric signal with a synchronous detection using the second reference signal generated by the reference signal generator, and generate a first monitor signal indicating the detected intensity and phase of the first reference signal and a second monitor signal indicating the detected intensity and phase of the second reference signal; and a controller configured to control the bias voltage of the optical modulator in a control scheme determined based on the first monitor signal and the second monitor signal.