Abstract

All-solid-state UV lasers have been in demand for various industrial and medical applications because of the convenient operation procedure and cost effectiveness as alternative to corrosive gas-based excimer laser. The performance of such lasers seems to depend on the capability and reliability of UV frequency converter. In thid decade, CsLiB₆O₁₀ (CLBO) and Gd_xY_1-xCa₄O(BO₃)₃ (GdYCOB) have been developed by the authors group. CLBO is the most effective nonlinear optical crystal to generate high-power fourth- and fifth-harmonics of Nd:YAG laser. GdYCOB is the first material which can achieve noncritical phase-matching (NCPM) condition for THG of Nd:YAG laser. The NCPM condition is advantageous owing to its large angular acceptance and the elimination of walk-off between fundamental and harmonic lights. On the other hand, reliability is very importmat for actual application of these crystals. Here, we will present about techniques to improve durability of NLO crystals for high-power UV light generation. For instance, we found that removal of surface polishing compound by means of ion beam etching can imrpove surface durability of CLBO. Also, we will discussed about photo-induced damages in GdYCOB and its solution.

© 2000 IEEE