Experimental analysis of overall thermal properties of Nd:La₂CaB₁₀O₁₉ crystals

Pure or rare-earth-ion-doped La₂CaB₁₀O₁₉ (LCB) is a promising optical material for nonlinear frequency conversion, laser and self-frequency doubling applications. In this paper, the thermophysical properties of Nd³⁺-doped LCB (Nd:LCB) crystals were measured and compared with those of pure and of Yb³⁺- and Er³⁺-doped LCB, as well as other borate nonlinear optical crystals. The melting points of rare-earth-doped LCB crystals are lower than that of pure LCB. Thermal expansion coefficients along the a, b, c, c*, a*, <110> and <110>* directions have been measured, and the principal expansion coefficients were calculated to be 1.85 × 10^-6, 4.13 × 10^-6 and 8.79 × 10^-6 K^-1. The measured specific heat of Nd:LCB is lower than that of pure LCB, resulting in a larger internal temperature gradient under irradiation by a pulsed laser beam. The measured thermal expansion anisotropy of Nd:LCB is stronger than that of pure LCB. The thermal conductivities of Nd:LCB along the c and c* directions are smaller than those along other crystallographic directions.