Anisotropic thermal, polarized spectroscopic properties and laser performances of Nd:YVO4 crystal from 20 K to 300 K

Abstract

Temperature-dependent anisotropic thermal and polarized spectroscopic properties of Nd:YVO₄ crystal from liquid hydrogen temperature (20 K) to 300 K have been investigated. Thermal properties, such as thermal conductivity and thermal expansion coefficient (TEC) were presented. The maximum thermal conductivity along a-axis and c-axis are 218.3 W/mK and 238.9 W/mK at ∼ 20 K, respectively, both are over one order of magnitude than that at room temperature. The TEC decreases progressively as temperature drops from room temperature to 20 K. Moreover, the polarized spectroscopic properties including absorption cross section, stimulated emission cross section and fluorescence lifetime have been measured to evaluate laser performance. Furthermore, we experimentally explore continuous wave laser performances under various temperatures. A maximum output power of 1.67 W is obtained at 20 K, corresponding to an optical–optical efficiency of 55.7 %, both are about 3.2 times better than that at room temperature. The near-diffracted-limited operation is also observed at 20 K. Thus, based on the large thermal conductivity, low thermal expansion and high emission cross section, high-power, high-beam-quality and highly efficient Nd:YVO₄ lasers can be developed at 20 K.