Patent ID: 6836622
Filing Date: 2004-12-28
Classification: G02F

Abstract:
An optical transmitter which outputs an optical pulse-train having double a frequency of a driving signal for transmission, said optical transmitter comprising:an optical modulator of Mach-Zehnder type; a light source which outputs light that is input into said optical modulator; a driving unit which inputs the driving signal into said optical modulator; a converting unit which converts a part of the optical signal output from said optical modulator into an electric signal; an extracting unit which extracts a frequency component of the driving signal contained in the converted electric signal obtained by said converting unit; a phase comparing unit which compares phases of the driving signal input into said driving unit and the frequency component of the driving signal extracted by said extracting unit; and a bias voltage control unit which controls a bias voltage to be applied to said optical modulator based on a result of the phase comparison.