Optical semiconductor devices

Abstract

The laser diode (100) includes: a semi-insulating substrate (3), a laser section (1) formed on the semi-insulating substrate (3), an optical modulator (2) formed on the semi-insulating substrate (3) and modulating the output light of the laser section (1), and a back electrode (19) formed on the underside of the semi-insulating substrate (3). The laser diode (100) is mounted on a mounting substrate (21), and the back electrode (19) is bonded to an electrode pattern (21a) on the mounting substrate (21). A first low-pass filter (25a) is connected between the cathode of the laser section (1) and a ground terminal (21h). A second low-pass filter (25b) is connected between the anode of the laser section (1) and a power supply terminal (21g). The electrode pattern (21a) has a floating potential. Furthermore, a third low-pass filter (25c) is connected between the electrode pattern (21a) and the ground terminal (21h).

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