Sumitomo Electric Device Innovations, Inc.

Ryutaro Takei

Takayuki Suzuki

Takeshi Irie

Tomoki Ito

Masatsugu Togasaki

Kazuhisa Ozaki

An optical transmitter includes an optical transmission unit, a drive unit, an arithmetic circuit, and a bias supply circuit. The optical transmission unit includes a laser element. The drive unit drives the laser element according to a first transmission signal. The arithmetic circuit generates a second transmission signal. The bias supply circuit superimposes the second transmission signal on a bias current of the laser element. An output of the arithmetic circuit containing the second transmission signal is a digital signal in a rectangular wave form based on a reference clock having a frequency lower than a reference clock frequency of the first transmission signal. The bias supply circuit includes a circuit element for inclining a rising portion and a falling portion of the output of the arithmetic circuit.

Optical transmitter

New method to control the optical transmitter is disclosed. The optical transmitter provides both of the ATC feedback loop and the APC feedback loop. When a failure occurs in the ATC feedback loop and the temperature sensor is unable to output an adequate signal any longer, the optical transmitter cuts the APC loop and operates the LD in constant conditions. The output of the monitor PD is transferred to the ATC loop to control the TEC based on the optical output of the LD.

Growing community of inventors

Yokohama, Japan

Ryutaro Takei