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We demonstrate the application of as-grown calcium barium niobate (CBN) crystal with random-sized ferroelectric domains as a broadband frequency converter. The frequency conversion process is similar to broadband harmonic generation in commonly used strontium barium niobate (SBN) crystal, but results in higher conversion efficiency reflecting a larger effective nonlinear coefficient of the CBN crystal. We also analyzed the polarization properties of the emitted radiation and determined the ratio of d32 and d33 components of the second-order susceptibility tensor of the CBN crystal.

Optical spectra and luminescence decay curves were measured for erbium-doped YVO(4) and GdVO(4) single crystals as a function of temperature in the 300 K-670 K temperature region. In spite of structural similarity the two systems studied display significantly different transition intensities and nonradiative relaxation rates. It was found in particular that the intensity of parasitic upconverted emission excited at 978 nm depends weakly on temperature for YVO(4):Er(3+), whereas it decreases monotonously with increasing temperature for GdVO(4):Er(3+) and becomes negligibly small at 670 K. It was concluded that GdVO(4):Er(3+) may be a promising laser active material operating at high thermal loading conditions encountered in high-power diode-pumped IR lasers.