Abstract

Deuterated L-arginine phosphate (dLAP) is a promising new crystal for frequency conversion of near-IR and visible lasers.¹ Reported values of the thermal coefficients of refraction of dLAP predict the existence of a unique property: temperature-insensitive phase-matching directions for second-harmonic generation. We used a Nd:YAG laser to measure the thermal rates of change of phase-matching angles in the principal dielectric planes of dLAP. For the type I phase-matching locus, we have found that the phase-matching angle relative to the alpha axis increases at a rate of 248 μrad/°C in the alpha-beta plane and decreases at a rate of 38.3 μrad/°C in the alpha-gamma plane, whereas for the type II phase-matching locus, the phase-matching angle increases at a rate of 237 μrad/°C in the alpha-beta plane and increases at a rate of 30.9 μrad/°C in the alpha-gamma plane. The opposite signs of the thermal rates of change of the type I phase-matching angles verify the existence of temperature-insensitive phase-matching directions in the type I second-harmonic generation phase-matching locus. Discrepancies between the predicted and measured thermal behavior of the dLAP phase-matching loci are attributed to errors in the reported values of the thermal coefficients of refraction.

© 1990 Optical Society of America