Single crystals of KBeBO3F (KBBF) up to 2 mm in thickness were grown by using a spontaneous nucleation method. The flux was composed of KF and B2O3, and the optimal ratio for growing KBBF single crystal thicker than 1 mm is suggested to be (1.0–1.5):(5.0):(0.7–1.2) (KBBF:KF:B2O3) in molar ratio. The ideal morphology of.KBBF is two sets of tabular facets and a set of rhombic facets. Surface morphology.was characterized both by optical microscopy and atomic force microscopy. Transmission spectra showed that high transmission was maintained up to 170 nm. Based on refractive index measurements, phase matching curves for types I and II were determined. Using a prism coupling method, the effective fourth harmonic generation for an Nd:YAB laser was realized in an 0.6-mm-thick KBBF sample. The output energy of the 266-nm beam was 0.282 mJ, and the conversion efficiency was 11.8%. A 183.6-nm laser over 1 mW was obtained from a Ti:sapphire second harmonic generation beam in an 0.8-mm KBBF sample. The conversion efficiency reached 2.3%. A 179.4-nm laser was also observed from a 358.7-nm laser by directly frequency doubling. This is the shortest wavelength obtained through nonlinear optical processes in a solid-state laser.

Pure and neodymium-doped gadolinium calcium oxoborate crystals of high quality were grown by the Czochralski method. The orientation of crystal was precisely determined, and the samples for measurements were prepared. Through synchrotron x-ray topography and high-resolution x-ray diffractometry, the twin structure was discovered. Some properties such as the figure of merit value, and dielectric, piezoelectric, and elastic constants were measured along with a discussion of the anisotropy of the laser properties.

The J-U relation of the KTP crystal along its z-axis under low DC field deviates from linearity, which is different from that of the crystal along the other two principle axis. The resistance of the crystal along its z-axis increases with the time under high DC stress and the crystal becomes dark. The dark color can be removed by annealing. Electrode reactions were also observed. The phenomena are related to the easy movement of ions along the z-axis of the KTP crystal.

Homogenous tetragonal potassium lithium tantalate niobate (KLTN) crystals were grown using the flux pulling method. A two-wave-mixing gain coefficient of 0.5cm−1 has been measured using undoped KLTN. The gain coefficient can be increased to 2.7 cm−1 after doping of 0.2wt% Fe. The “cat” self-pumped phase conjugator was performed, for the first time, with KLTN:Fe crystal. We obtained a reflectivity of 14% and a response time less than 3 seconds using a frequency-doubled Nd:YAG quasi-continuous laser.