An rf‐sputtered thin film of LiNbO3on a sapphire substrate was used as a waveguide for optical frequency doubling. Employing a Nd:YAG laser and a tunable dye laser, whose output was used to pump a stimulated Raman cell, the TM&ohgr;0 → TM2&ohgr;2up‐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.