Characterization of laser crystal Yb:CaYAlO_4

Abstract

Yb:CaYAlO4 (Yb:CYA) crystals with good optical qualities have been grown by the Czochralski method. The detailed polarized spectral properties, including absorption and fluorescence, were investigated. The results reveal a broadband emission feature (FWHM=77 nm at σ polarization). The fluorescence lifetime has been measured using the powder concentration dilution method, and the intrinsic lifetime was found to be 426 μs. The thermal properties, including specific heat, thermal expansion, and thermal diffusion coefficients, have been investigated. The thermal conductivities were calculated to be 3.6 and 3.2 W/m/K along the a and c axes, respectively, at room temperature. The CW laser performances have been studied for both π and σ polarizations. The slope efficiencies of 55.4% and 41.4% were obtained for π- and σ-polarized operations, respectively. All the results show that Yb:CYA crystals should be excellent candidates as a laser medium for efficient and ultrafast lasers in the 1 μm region.