Second harmonic generator and method of fabrication thereof

摘要

A second harmonic generator having a wide acceptance of bandwidth of temperature and/or a high conversion efficiency and a method of fabrication thereof are disclosed. An equidistant arrangement of pole-inverted grating having a rectangular sectional profile and the direction of spontaneous polarization opposite to that of a substrate within an optical waveguide has been known to produce a high conversion efficiency of the second harmonic generator A second harmonic generator having such a structure, which has so far been impossible to fabricate, is formed utilizing the liquid-phase epitaxial method and the ion-implanting method. Further, the substrate and the optical waveguide are formed of the same type of material. The temperature coefficient of the refractive index in the direction perpendicular to the substrate surface is rendered substantially equal to that of the optical waveguide, thereby improving the acceptance of bandwidth of temperature and making possible practical applications of the second harmonic generator.