Second-harmonic generation of ferroelectric potassium lithium niobate crystals

The second-harmonic generation (SHG) properties of a potassium lithium niob ate (KLN) crystal with the size of 8x20x43mm(3) were studied in detail. The KLN crystal was grown from a melt consisting of 32 mol% K2O, 24mol% Li2O a nd 44mol% Nb2O5 (denoted as the melt 32 : 24 : 44) by the top-seeded soluti on growth (TSSG) method. The ferroelectricity of the KLN crystal was reveal ed by the marked dielectric anomaly at the Curie temperature. The full-widt hs at half maximum (FWHMs) of the wavelength- and temperature-tuning curves of a 4-mm-long KLN crystal sample were found to be 0.6 nm and 2 degreesC, respectively. The SHG conversion efficiency of this crystal was studied and estimated to be 0.03%/W for an input power of 748 mW. The CW tunable blue laser covering the range of 431.1-437.6 nm was achieved by tuning the cryst al temperature in the range of 24-80 degreesC. The crystal studied in this paper is more inhomogeneous and has lower SHG efficiency than the KLN cryst al grown from the melt 31 : 26 : 43. which has higher Li2O content.