High-power and high-efficiency frequency doubling of Q-switched Nd:YAG lasers in periodically poled KTP

Summary form only given. Periodically poled ferroelectric crystals such as KTiOPO/sub 4/ (PPKTP) and LiNbO/sub 3/ (PPLN) are increasingly being used as efficient frequency converters due to their high nonlinearities and engineerable phase-matching characteristics. The photorefractive effect and relatively small aperture size of available PPLN crystals limit their applicability for high-pulse-energy green-blue light generation. On the other hand, the PPKTP which, reportedly, sustains higher optical intensity and can be poled over larger aperture thickness has a potential for the generation of high-power green-blue radiation. In this work we report on the investigation of frequency doubling by PPKTP of the flash-lamp pumped Q-switched Nd:YAG lasers. Special attention has been paid to the efficiency limitations at high pulse energies.