A second harmonic wave-generating element

摘要

A second harmonic wave-generating element for generating a second harmonic wave from a fundamental wave, has an optical waveguide layer (2A) made of first epitaxial material having a fundamental composition of K3Li2-X(Nb1-YTaY)5+XO15+Z, an underclad part (1) made of a single crystal substrate or a second epitaxial material having a fundamental composition of K3Li2-X+A(Nb1-Y-BTaY+B)5+X-AO15+Z, an overclad part (4A) made of third epitaxial material having a fundamental composition of K3Li2-X+C(Nb1-Y-DTaY+D)5+X-CO15+Z and formed on and contacting the optical waveguide layer, wherein X=0.006 to 0.5, Y=0.00 to 0.05, A=0.006 to 0,12, B=0.005 to 0.5, C=0.006 to 0.12, D=0.005 to 0.5, X-A≤0, X-C≥0, ¦A-C¦≤0.006, and ¦B-D¦≤0.005). <IMAGE>