Patent ID: 7609737

Claim:
A nitride semiconductor laser device comprising: a nitride semiconductor substrate; a nitride semiconductor layer that has an n-type semiconductor layer, an active layer and a p-type semiconductor layer laminated on or above the nitride semiconductor substrate, and has a stripe-shaped waveguide region for laser light; and an emission-side end surface protective film and a rear-side end surface protective film opposed thereto on the end surfaces of resonance sandwiching the waveguide region, wherein the nitride semiconductor substrate has a luminescent radiation region that absorbs light emitted from the active layer and emits luminescent radiation with a wavelength longer than the wavelength of the emitted light, and the rear-side end surface protective film includes a first end surface protective film having a higher reflectivity for the wavelength of the luminescent radiation, and a second end surface protective film having a higher reflectivity for the wavelength of the emitted light from the active layer, the emission-side end surface protective film includes a third end surface protective film having a higher reflectivity for the wavelength of the luminescent radiation and having a lower reflectivity for the wavelength of the emitted light from the active layer, the emission-side end surface protective film covers the stripe-shaped waveguide region or an emission-side of the end surface of the resonance, the end surface protective films further cover both end surfaces of the nitride semiconductor substrate, and wherein the second end surface protective film is sandwiched by the nitride semiconductor layer and the first end surface protective film.