Second-harmonic generation in GaSe crystals investigated with the Maker fringe technique

Frequency doubling in z-cut GaSe crystals was studied at a fundamental wavelength of 1579 nm using the Maker fringe technique. The signals show a pronounced fine structure due to Fabry-Perot resonances of the fundamental wave in the plane-parallel crystals of high refractive indices. In the data evaluation, the birefringence of the samples must be taken into account. The fine structure is described using a ray-tracer algorithm which accounts for the finite diameter of the incident beam. For the nonlinear coefficient a value of d(22) greater than or equal to 72 +/- 6 pm/V is obtained. (C) 1997 Published by Elsevier Science B.V.