Abstract

By using integrated optical waveguides, high conversion efficiencies can be obtained for SHG at moderate power levels. The best results have so far been obtained with Ti:LiNbO₃ waveguides [1,2]. The material birefringence is then utilized to fulfil the phase-matching condition. SHG using the fundamental wavelength ~ 0.8 μm, which is of considerable practical interest, cannot, however, be phase-matched in this way. The wavelength dispersion is in this case so large that it cannot be compensated for by the birefringence of LiNbO₃. Promising results for SHG in proton-exhanged waveguides using semiconductor lasers at 0.84 μm wavelength have, however, been reported [3,4], with the frequency doubled light generated as a substrate mode, Cerenkov radiation. Conversion efficiencies have been reported [3], that are comparable to guided-guided wave interactions in Ti:LiNbO₃ waveguides. The Cerenkov scheme benefits from the facts that the largest nonlinear coefficient d₃₃ is used, and that proton-exchanged waveguides can be used, allowing strong mode confinement.

© 1989 Optical Society of America