Patent ID: 7356056
Filing Date: 2008-04-08
Classification: H01S,H04N

Abstract:
1. A coherent light source comprising: a semiconductor laser provided with an active region and a distributed Bragg reflection region; a light wavelength conversion element that is made of non-linear optical crystal and converts a wavelength of a laser beam emitted from the semiconductor laser; a photo detector that measures a higher harmonic output from the light wavelength conversion element; current injection means for applying currents independently to the active region and the distributed Bragg reflection region; current control means for controlling the current injection means on the basis of the higher harmonic output measured in the photo detector to fix an oscillation wavelength of the semiconductor laser to an inclined portion within a phase matching wavelength spectrum of the light wavelength conversion element; pulse current injection means for applying a pulse current to at least one region selected from the active region and the distributed Bragg reflection region; and pulse current control means for controlling the pulse current injection means on the basis of the higher harmonic output measured in the photo detector to change the oscillation wavelength of the semiconductor laser to a desired value at the inclined portion within the phase matching wavelength spectrum of the light wavelength conversion element and to change the higher harmonic output.