Patent ID: 6804282
Filing Date: 2004-10-12
Classification: H01S

Abstract:
A semiconductor laser device comprising:a semiconductor laser element having an effective refractive index of nc, a front end face through which light generated in the semiconductor laser is emitted, and a back end face at which the light is reflected back into the semiconductor laser; and a multilayer film on the front end face of said semiconductor laser element wherein, said multilayer film includes a first film with a refractive index of n1 and a second film with a refractive index of n2, alternately laminated, said first film being in contact with said first end face, and the refractive index n1 and the refractive index n2 satisfy n1nc)1/2 n2>(nc)1/2, and said multilayer film has a reflectivity varying with wavelength of light produced by said semiconductor laser element, the reflectivity having a local maximum at a wavelength &lgr;1 within a wavelength region and having respective minimums at wavelengths &lgr;2 and &lgr;3 on a shorter-wavelength side and a longer-wavelength side of the wavelength &lgr;1, the reflectivity increasing at wavelengths shorter than the wavelength &lgr;2 and at wavelengths longer than the wavelength &lgr;3.