Patent ID: 8891572

Claim:
A semiconductor laser device comprising: a semiconductor laser chip having an emission surface and a reflection surface which are opposing end surfaces of a resonator, the semiconductor laser chip including an active layer having a structure in which an In x1 Ga 1-x1 N quantum well layer and an In x2 Ga 1-x2 N barrier layer, wherein x1>x2 are layered alternately; and a photodiode for detecting light that exits from the reflection surface side, the photodiode having a sensitivity which rises as a wavelength of the exiting light lengthens in a range from 300 nm to 500 nm, wherein the emission surface has a first dielectric multilayer film formed thereon and the reflection surface has a second dielectric multilayer film formed thereon, and wherein the semiconductor laser chip has an oscillation wavelength λ 1 ; wherein the first dielectric multilayer film on the emission surface has a reflectance property which peaks at λ f ; and wherein the second dielectric multilayer film on the reflection surface has a reflectance property which peaks at λ r ; and wherein λ f <λ 1 >λ r .