High efficiency infrared generation by difference-frequency mixing using tangential phase matching

Abstract

Measurements have been made of the energy generated in the wavelength region 3.3 to 4.0 µm, by difference-frequency mixing between a tunable dye laser and a Nd:YAG laser in lithium niobate. The highest mixing efficiencies have been observed with the beams aligned in a non-collinear geometry. It is demonstrated that this non-collinear geometry corresponds to the tangential phase-matching condition which increases the acceptance angle of a second-order nonlinear interaction over that achieved in a non-critically phase-matched geometry