Versatile temperature-insensitive second-harmonic generation by compensating thermally induced phase-mismatch in a two-crystal design

We propose and experimentally demonstrate a novel second-harmonic-generation (SHG) scheme capable of supporting temperature-insensitive phase-matching (PM) at various laser wavelengths. This versatile temperature-insensitive PM is designed by using two cascaded crystals with opposite signs of temperature derivation of phase-mismatch, in which the temperature-induced phase-mismatch in the first crystal is well compensated in the second crystal. Two application examples are studied at the typical wavelengths of similar to 1.0 and 1.5 mu m, respectively. The proof-of-principle experiment, using two crystals of LiB3O5 (LBO) and KH2PO4 (KDP), demonstrates that the temperature-acceptance of PM can be 2-3 times larger than that of using a traditional single crystal. The proposed two-crystal design may provide a promising route to high-average-power SHG at various laser wavelengths. (C) 2012 by Astro, Ltd.