| 摘要 |
PURPOSE:To remarkably improve the operation lifetime of the laser element coating one of a resonant surface thereof with a dielectric film having approx. 1/4n of output light wavelength and the other of the resonant surface thereof with a dielectric film having approx. 1/2n of output light wavelength, where n represents the refractive index of the dielectric film. CONSTITUTION:The resonant for determining the lifetime of a semiconductor laser is deteriorated by the laser light irradiated from the resonant surface and O2 in the atmosphere by the optochemical reaction. The reaction is proceeded in proportion to the light energy in the vicinity of the resonant surface. When the resonant surface is accordingly coated with a dielectric film having smaller transmissivity than the refractive index of the crystal, the reflectivity on the resonant surface is varied with the thickness of the film, and when the thickness of the film is controlled, the internal energy can be reduced. The wavelength in the laser light is represented by lambdal and when an Al2O3 film having a refractive index n lambdal is deposited in a thickness of lambdal/4n on one of the resonant surfaces, the internal energy becomes zero on the other surface, and the film can be eliminated, but a film having lambdal/2n is formed thereon to supplement it. According to this configuration, the oxidation of the resonant surface can be prevented, and the operation lifetime of the laser element can be improved. |
