Abstract
To avoid the deviation of K_3Li_<2-x>Nb_<5+x>O_<15+2x> (KLN) crystal composition during the growth, an improved Czochralski technique , so called continue-charged Czochralski method, has been employed to offset the compositional change in melt during the growth by continually throwing calcined powder into the crucible, Using this method, the KLN crystal with composition of K_<3.00>Li<1.80> Nb_<5.20>O_<15.4> has been grown from melt of K_<3.00>Li_<2.63>Nb_<4.37> O_<13.74>-A 30 mm-long crystal was investigated for compositional deviation by measuring its transition temperature. The crystal was divided into 7 equal parts along the pulling direction, and their transition temperature were measured by a DSC equipment. The transition temperature of all samples were coincident with each other and determined to be 534℃ , indicating that the crystal is compositional deviation free and its concentration of Nb is 52 mol%. The crystals were transparent with an absorption edge at 370 nm, and showed a small optical absorption in the 420-900 nm region. Both ordinary and extraordinary optical indices were measured by the least declinate method, and then fitted to the Sellmeier's dispersion relation. The wavelength of second harmonic generation at the noncritical matching angle was determined at 816 nm. A blue SHG output beam with wavelength of 408 nm was observed. The nonliner optic coefficient is larger than that of LiNbO_3.
