Patent ID: 6516017
Filing Date: 2003-02-04
Classification: H01S

Abstract:
A semiconductor laser device comprising:a laser unit having a plurality of semiconductor lasers, each laser producing light at a different oscillation wavelength, the oscillation wavelength produced by each semiconductor laser varying with temperature of said semiconductor laser producing the light; an optical modulation unit having a single electroabsorption modulator for optically modulating laser light produced by said laser unit in response to an applied principal bias voltage, said electroabsorption modulator having a band gap wavelength varying with voltage applied to said electroabsorption modulator and differing by &Dgr;&lgr; from the oscillation wavelength being produced by one of said semiconductor lasers; a coupling unit coupling said laser unit and said optical modulation unit so that laser light from each of said semiconductor lasers is incident on said electroabsorption modulator; a temperature control unit for controlling, by heating and cooling, temperature of said laser unit and of said optical modulation unit, said laser device outputting light at at least twice as many oscillation wavelengths as number of semiconductor lasers in said laser unit by selectively controlling the temperature of said laser unit at at least two different controlled temperatures; a laser selection unit for selecting and operating one of said plurality of semiconductor lasers in said laser unit; an offset bias control unit for selective application of an offset bias voltage to said electroabsorption modulator of said optical modulation unit for offsetting the principal bias voltage applied to said electroabsorption modulator to adjust the band gap wavelength of said electroabsorption modulator so that a constant &Dgr;&lgr; is maintained for the oscillation wavelength being produced by said semiconductor laser selected and operated by said laser selection unit; and a controller for specifying, for said laser selection unit, the one of said plurality of semiconductor lasers to be operated, based on an external command specifying a wavelength of light to be produced, and for controlling operation of said temperature control unit and said offset bias control unit to maintain the constant wavelength difference &Dgr;&lgr;.