VARIABLE-WAVELENGTH LIGHT SOURCE CONTROL CIRCUIT AND METHOD USING DIRECT MODULATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a variable-wavelength light source control circuit which can easily control an optical signal outputted from a semiconductor laser to a required wavelength by using a direct modulation system with a simple circuit construction, while keeping an output light intensity and an extinction ratio of the semiconductor laser constant. SOLUTION: The semiconductor laser 1 outputs the modulated optical signal corresponding to a drive current and a bias current. A wavelength information extracting part 2 detects the wavelength of the modulated optical signal which is outputted. A temperature control unit 3 controls an environmental temperature of the semiconductor laser 1 so that the detected wavelength is a required value. A temperature computing part 4 computes a device temperature of the semiconductor laser 1 based on the detected wavelength. A current set value computing part 5 computes the bias current and drive current needed for obtaining prescribed output light intensity and extinction ratio at a computed device temperature. A bias current control unit 7 supplies a computed bias current, and a drive current control unit 6 supplies a computed drive current individually to the semiconductor laser 1 according to the modulated signal. COPYRIGHT: (C)2004,JPO&NCIPI