Fundamental walkoff compensated SHG in KTP and LBO

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A fundamental walkoff-compensated type II SHG scheme has been analyzed and its usefulness has been experimentally demonstrated for KTP and LBO.Maximum SH power was obtained at a crystal cut angle of 28.5 deg and an incident angle of 7 deg for KTP at a 1064nm fundamental wavelength, and a 20% power enhancement was observed in 12 nun long KTP compared with a conventional 24 deg cut crystal. For LBO, FWC type II SHG was found to ke place in the crystal cut at 40 deg from the Z (b) to the Y(-c) axes. Double power enhancement was observed for 10mm-long FWC type II LBO than for conventional type II LBO (20-deg cut) and almost coincides with LBO type I SHG power at an optimum focusing condition. this proves the importance of walkoff compensation between two fundamental beams in type II SHG.This scheme is also suitable for nonlinear device application because incident angles are finite (not normal to the SHG crystal) and do not retroreflect, which would result in unstable laser oscillation.