Patent ID: 8488643

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 mask structure array formed on the first layer, the mask structure including members having a second refractive index and arrayed periodically in the in-plane direction of the substrate, or including a member having the second refractive index and including openings arrayed periodically in the in-plane direction of the substrate, and a pitch of the mask structure array is equal to or more than 4.4 times of an oscillation wavelength λ; a third layer formed on the first layer and the mask structure and having a third refractive index differing from the first refractive index and the second refractive index; and the photonic crystal formed on the third layer, wherein a concave-convex periodic structure, which is constituted by the first layer and the mask structure, is configured such that a reflection peak wavelength of 0-th order diffracted light and a reflection peak wavelength of first-order diffracted light differ from each other, and intensity of the 0-th order diffracted light reflected from the concave-convex periodic structure is larger than intensity of the first-order diffracted light reflected from the concave-convex periodic structure at the wavelength λ.