Patent ID: 7082146

Claim:
A device for inspecting a wavelength-variable semiconductor laser having at least an active region, a phase control region, and a distributed Bragg reflector (DBR) region, comprising: a power source for supplying an active current to the active region, a phase current to the phase control region, and a DBR current to the DBR region; a photo-detector for detecting an output intensity of laser beam emitted from the wavelength-variable semiconductor laser; a second harmonic generation (SHG) element that that is inserted into a light path from the wavelength-variable semiconductor laser to the photo-detector; and a control circuit provided between the photo-detector and the wavelength-variable semiconductor laser; wherein when a constant active current is supplied to the active region, the phase current that is supplied to the phase control region and the DBR current that is supplied to the DBR region are each changed independently, the output intensity of the harmonic light that is wavelength converted by the SHG element is detected by the photo-detector, and the phase current and the DBR current corresponding to points of change in the output intensity are determined by the control circuit, and wherein the control circuit calculates a current ratio ΔIdbr/ΔIph of the DBR current to the phase current from a DBR current difference ΔIdbr corresponding to the points of change in the output intensity that are obtained when the DBR current is changed, and a phase current difference ΔIph corresponding to the points of change in the output intensity that are obtained when the phase current is changed.