Modeling of frequency doubling and tripling with measured crystal spatial refractive-index nonuniformities

Efficient frequency doubling and tripling are critical to the successful op eration of inertial confinement fusion laser systems such as the National I gnition Facility currently being constructed at the Lawrence Livermore Nati onal Laboratory and the Omega laser at the Laboratory for Laser Energetics. High-frequency conversion efficiency is strongly dependent on attainment o f the phase-matching condition. In an ideal converter crystal, one can obta in the phase-matching condition throughout by angle tuning or temperature t uning of the crystal as a whole. In real crystals, imperfections in the cry stal structure prohibit the attainment of phase matching at all locations i n the crystal. We have modeled frequency doubling and tripling with a quant itative measure of this departure from phase matching in real crystals. Thi s measure is obtained from interferometry of KDP and KD*P crystals at two o rthogonal light polarizations. (C) 2001 Optical Society of America.