Patent ID: 8427732

Claim:
An uncooled optical semiconductor device comprising: a semiconductor laser outputting laser light in response to a current supplied to the semiconductor laser; an electric field absorption optical modulator on which the laser light is incident, wherein the electric field absorption optical modulator has an anode and a cathode, modulates the laser light by absorption of the laser light in a quantity that varies with a bias voltage applied to the electric field absorption optical modulator, and generates a light absorption current in response to the bias voltage applied and the absorption of the laser light; a monitor photodiode monitoring and detecting backlight emitted by the semiconductor laser and producing a photocurrent in response to the backlight detected; an auto power control circuit responding to the backlight detected by the monitor photodiode by feeding back to the semiconductor laser a current produced in response to the photocurrent, independent of temperature of the semiconductor laser; and a bias circuit feeding back to the electric field absorption optical modulator an average value of the light absorption current and thereby controlling a bias voltage applied to the electric field absorption optical modulator, irrespective of temperature of the electric field absorption optical modulator.