SEMICONDUCTOR LASER BEAM SOURCE AND MODULATION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To realize a semiconductor laser light source which maintains the wavelength of a laser beam and which can perform a light intensity modulation and to realize a modulation method for the semiconductor laser light source. SOLUTION: A semiconductor laser which is provided with an active region and a distributed Bragg reflector(DBR) region in which a DBR is formed is installed. A heater which gives a heat quantity to the semiconductor laser is installed. A drive circuit which modulates an injection current to the active region and which controls the amount of the injection current to the heater in such a way that the sum of the heat quantity transmitted to the DBR region from the active region and the heat quantity transmitted to the DBR region from the heater becomes nearly definite is installed. The laser beam which is output by the semiconductor laser is modulated in light intensity.