PURPOSE: To monolithically integrate a semiconductor and SHG element so as to improve the coupling efficiency between laser light and the SHG element by providing an electrode which impresses an electric field in the film thickness direction to a secondary higher harmonics generating thin-film optical waveguide.

CONSTITUTION: A secondary higher harmonics generating optical wveguide section is constituted of a ridge type optical waveguide composed of a ZnSxSe1-x (x=0.5 to 1.0) clad layer 303, super lattice nonlinear optical waveguide layer 304 of ZnSe and ZnS, and ZnSxSe1-x (S=0.5 to 1.0) clad layer 305 and a ZnSxSe1-x(x=0.1) film covering the waveguide. In addition, an electrode 307 is provided and, when a voltage is applied across electrodes 307 and 306, an electric field can be impressed upon the super lattice optical waveguide layer 304. The position of the layer 304 is made coincident with that of a GaAs active layer 204. Therefore, most of laser light can impinge on the secondary higher harmonic generating optical waveguide layer 304 with little loss.