Patent ID: 8374205

Claim:
A vertical cavity surface emitting laser that includes a plurality of semiconductor layers laminated on a substrate, the layers including a lower multilayer reflecting mirror, an upper multilayer reflecting mirror, and a first active layer arranged between the mirrors, and that oscillates at a wavelength λ 1 , wherein a resonator is formed by the upper multilayer reflecting mirror and the lower multilayer reflecting mirror, the resonator has a structure that generates longitudinal multimode including: a first longitudinal mode in which a resonant wavelength is λ 1 , and in which a confinement factor of the first active layer is Γ 1 and a gain at the resonant wavelength λ 1 in a gain spectrum originated from the first active layer is g 1 (g 1 ≠0); a second longitudinal mode in which the resonant wavelength is λ 2 and which is adjacent to the first longitudinal mode, and in which the confinement factor is Γ 2 and the gain at the resonant wavelength λ 2 is g 2 (g 2 ≠0); and a third longitudinal mode that is different from the second longitudinal mode in which the resonant wavelength is λ 3 and which is adjacent to the first longitudinal mode, and in which the confinement factor is Γ 3 and the gain at the resonant wavelength λ 3 is g 3 (g 2 >g 3 ), and the first active layer is arranged at a position shifted from a standing wave loop of the first longitudinal mode formed in the resonator, oscillation of the second longitudinal mode with a large gain of the first active layer among the first to third longitudinal modes is suppressed, and single longitudinal mode oscillation based on the first longitudinal mode is allowed.