Semiconductor laser device

A semiconductor laser device comprising:

• a semiconductor element layer having a light emitting layer;
• a first cavity facet formed on an end portion on a light emitting side of a region of said semiconductor element layer including said light emitting layer;
• a first insulating film in which a first nitride film, a first intermediate film including at least one of a first oxide film and a first oxynitride film and a second nitride film are formed on said first cavity facet in this order from the side of said first cavity facet;
• and
• a second insulating film, formed on said first insulating film, including at least one of a second oxide film and a second oxynitride film, wherein
• the thickness t1 of said first nitride film, the thickness t2 of said first intermediate film and the thickness t3 of said second nitride film are set to be t1<λ/(4×n1), t2<λ/(4×n2) and t3<λ/(4×n3) respectively when the wavelength of a laser beam emitted by said light emitting layer is λ and the refractive index of said first nitride film, the average refractive index of said first intermediate film and the refractive index of said second nitride film are n1, n2 and n3 respectively.