WAVELENGTH CONVERSION ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a wavelength conversion element which has optical damage resistance and long-term reliability, and can achieve a long and highly efficient nonlinear optical effect by achieving a long effective nonlinear interaction length while satisfying both a fundamental mode propagation condition and a manufacturing tolerance.SOLUTION: The wavelength conversion element comprises: a waveguide core 2 that has a ridge structure and is composed of a nonlinear optical crystal having a cyclic polarization inversion structure; a base substrate 1 bonded to the waveguide core by direct bonding and including a SiO2 optical crystal; and an overclad layer 3 formed so as to embed the waveguide core therein. A refractive index n of the overclad layer satisfies 2.0≤n≤2.13 with respect to light of wavelength 1.56 μm, and a thickness x of the overclad layer satisfies y≤x≤y+1.0 μm with respect to a height y of the waveguide core.