Abstract

Small efficient light sources in the visible wavelength region are of considerable interest for various uses. An attractive approach for such a light source is to utilize nonlinear frequency conversion of laser diode radiation in an integrated optical waveguide. The best results for such processes have been achieved in LiNbO₃ waveguides. The phase matching condition for second harmonic generation (SHG) can only be fulfilled for wavelengths around 1.08 μm in this material. As there are no high power laser diodes available in this wavelength region, very few experiments on frequency conversion in waveguides have been reported. Various approaches for circumventing the phase matching problem to utilize laser diodes around 0.83 μm for SHG is known. Taniuchi and Yamamoto¹ generated blue SHG in the form of Cerenkov radiation and Webjorn et al.² made use of a quasi-phase matching structure. An alternative approach is to utilize sum frequency generation (SFG) instead of SHG. It turns out that sum frequency generation of light from two laser diodes can be phase matched in Ti.-LiNbO₃ waveguides at room temperature if the wavelengths are correctly chosen ~0,85 and 1.3 μm. This report describes the first experiments on sum frequency generation of laser diode light in such waveguides.

© 1990 Optical Society of America