Abstract

In recent years the blue-light source obtained by second-harmonic generation (SHG) in quasi phase matching (QPM) acquired a touch of reality because of its high efficiency of wavelength con version. A module consisting of a QPM-SHG device and an infrared laser diode has been obtained at a power level of several milliwatts and has arrived at the stage for establishing the procedures for production. In fabricating these devices, ion indiffusion,^1-4 electron-beam (EB) drawing,^5-7 electric-field induction by EB^8,9 (EFIEB), or direct electric field application^10,11 was performed for obtaining domain inversion. Although a deep and fine inverted domain is possible in EB drawing, EFIEB, and direct electric-field application, it is difficult to obtain a homogeneous domain-inverted structure. Etching in acids, cvhich employs the difference in the etching rates between the 180 domains, is a simple approach for checking the homogeneity.

© 1995 Optical Society of America