Frequency doubling in a LiNbO₃ thin film deposited on sapphire

An rf-sputtered thin film of LiNbO3 on a sapphire substrate was used as a waveguide for optical frequency doubling. Employing a Nd laser and a tunable dye laser, whose output was used to pump a stimulated Raman cell, the TM0ω → TM22ω up-conversion process was investigated in detail, and the phase-matched nature of this process was demonstrated. The conversion efficiency was estimated to be about 10-3.