Critical issues of materials selection for frequency conversion

Tunable laser sources ranging from UV visible to IR may be achieved by frequency conversion of lasers at fixed or tunable output using nonlinear output. The authors discuss the critical issues of the selection of nonlinear crystals for various applications. They compare the performance of various crystals including KDP, KD*P, CD*P, CD*A, urea, and some new crystals such as KTP, β-BaB/sub 2/O/sub 4/(BBO), and LAP. The important features of BBO and its applications for the generation of visible and UV sources from YAG and dye lasers are emphasized. Specific systems to be discussed and compared among various nonlinear crystals include (1) three-color output from a YAG laser combining CDA (type l doubling) and KDP (type ll tripling); (2) intra-cavity SHG using LilO/sub 3/ and KTP; (3) SHG and OPO using urea and BBO for the generation of UV sources from YAG and dye lasers