Patent ID: 8259386

Claim:
A wavelength conversion element that has an optical waveguide and that converts a wavelength of incoming light input from one end of the optical waveguide and outputs outgoing light from the other end of the optical waveguide, the wavelength conversion element comprising: a first crystal composed of Al x Ga (1-x) N (0.5≦x≦1); and a second crystal having the same composition as that of the first crystal, wherein the first and second crystals form a domain-inverted structure in which a polarization direction is periodically reversed along the optical waveguide, the domain-inverted structure satisfies quasi phase matching conditions with respect to the incoming light, and at least one of the first and second crystals has a dislocation density of 1×10 3 cm −2 or more and less than 1×10 7 cm −2 .