Second harmonic generation element and a process for producing the same

摘要

A second harmonic generation element including a single crystal substrate having a fundamental composition of K3Li2-2x(Nb1-yTay)5+5z O15-x+12.5z and an optical waveguide made of an epitaxial film with a fundamental composition of K3Li2-2a(Nb1-bTab)5+5cO15-a+12,5c and optical index different from that of the single crystal substrate, wherein: - 0.5 ≤ a, x ≤ 0.625 0 ≤ b, y ≤ 0.5 0.8 ≤ (5 - 2x)/(5 + 5z), (5 - 2a)/(5 + 5c) ≤ 1.2