OPTICAL TRANSMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To make a bias voltage applied to an external optical modulator precisely follow the optimum bias variation caused by the DC drift as to an optical transmission device equipped with the external optical modulator which modules the carrier light from a light source with an electric signal. SOLUTION: A bias voltage control circuit 150 controls the bias voltage that a bias application unit 105 applies to the external optical modulator 110 so that the quantity of secondary distortion that is generated at the light signal outputted from the external modulator 110 becomes minimum.