Type-II second-harmonic generation and sum-frequency mixing in uniform KTiOPO4 channel waveguides

Abstract
Type‐II second‐harmonic generation was investigated in channel waveguides fabricated in potassium titanyl phosphate (KTiOPO4) crystals by ion exchange. The birefringence of the guided‐wave structure was used to provide phasematching. A green (509 nm) output power of 0.25 mW was produced by frequency doubling the 1018‐nm output of a titanium:sapphire laser; this power is 200 times greater than what would be obtained in the corresponding bulk interaction. Phasematching for second‐harmonic generation was found to have broad tolerances with respect to temperature and wavelength. Blue light at 483 nm was produced by sum‐frequency mixing of 1064‐nm and 883‐nm light.