Patent ID: 7813391

Claim:
A method of controlling a semiconductor laser that has a first wavelength selection portion having a heater and a second wavelength selection portion having a different wavelength property from the first wavelength selection portion, and is mounted on a temperature control device, comprising: an initial step of starting a laser oscillation of the semiconductor laser; a first step, after the initial step, of correcting a temperature of the temperature control device according to a detection result of a wavelength detector that is a detected output wavelength of the semiconductor laser; and a second step, after the first step, of controlling the heater of the first wavelength selection portion so that changes in differentials between the wavelength properties of the first wavelength selection portion and the second wavelength selection portion are reduced, the differentials being caused by temperature corrections brought about by the temperature control device, wherein one of the first and second wavelength selection portions has an optical waveguide having a first region that has a diffractive grating, and a second region that is connected to the first region and acts as a spacer, and the other of the first and second wavelength selection portions is an active region having another first region that has a diffractive grating and another second region that is connected to the another first region and acts as a spacer.