Patent ID: 8442086

Claim:
A photonic-crystal surface emitting laser including an active layer and a photonic crystal, which has a resonance mode in an in-plane direction of a substrate, and oscillating at a wavelength λ, the photonic-crystal surface emitting laser comprising: a first layer having a first refractive index; a second layer formed on the first layer and having a second refractive index differing from the first refractive index; a mask structure formed on the second layer and having a third refractive index differing from the second refractive index, the mask structure being arraying members; a fourth layer formed on the second layer and the mask structure and having a fourth refractive index differing from the third refractive index; and the photonic crystal formed on the fourth layer, wherein an optical film thickness of the mask structure is not an integer multiple of a half of the wavelength λ, and reflectivity taken when laser light enters a multilayer structure including the first layer, the second layer, the mask structure, and the fourth layer from the fourth layer side is lower than reflectivity at an interface between the second layer and the first layer.