Growth and anisotropic thermal properties of biaxial Ho:YAlO3 crystal

Abstract

Ho: YAlO 3 ͑YAP͒ crystal with large size and good optical quality has been grown by the Czochralski method. Thermal properties of the as-grown Ho:YAP crystal have been investigated by measuring the temperature-dependent, anisotropic thermal expansion, specific heat, thermal diffusion, and thermal conductivity. The results show that Ho:YAP crystal possesses a large anisotropic thermal expansion and good thermal conductivity. The calculated average thermal expansion coefficients along a, b, and c axis are ␣ a = 9.18ϫ 10 −6 / K, ␣ b = 1.94ϫ 10 −6 / K, and ␣ c = 7.61ϫ 10 −6 / K from 293.15 to 770.15 K. The thermal conductivities along a, b, and c axis are up to 11.6, 9.9, and 12.3

Ho:YAG single crystal fiber: fabrication and optical characterization

“…In comparison with bulk Ho:YAG data in [15,17], the measured σ abs and σ emi are about half of the bulk data, several reasons may contribute to this reduction in measurements. First, due to the segregation effect of the Ho ions, the SCF may contain fewer Ho ions than the source rod or their distribution [18]. The over-estimated Ho ion concentration will result in a lower cross section coefficient calculation.…”

Growth, Thermal, and Optical Properties of a Novel Mid-Infrared Ho:LuYAP Laser Crystal

“…The thermal behaviors have a significant impact on the actual performance of laser crystal and are directly related to the crystal thermal lensing effect, which mainly includes expansion coefficients, thermal diffusivity (λ), specific heat ( C p ), and thermal conductivity (κ). Since the a -axis of the YAP crystal has the best laser performance, only the a -axis of LuYAP crystal was characterized and evaluated here. The measured expansion curve can be calculated by the following formula to obtain thermal expansion coefficient. Here, is the average linear thermal expansion coefficient in the range T 0 to T , and Δ T and L 0 are changes of sample length and temperature, and L 0 is sample length at T 0 .…”

Growth, thermal, and spectroscopic properties of a 2.911 μm Yb,Ho:GdYTaO4 laser crystal

“…where L 0 is the sample length at room temperature and ΔL is the change of the length in the temperature range ΔT. 24 In this case, the average thermal expansion coefficients along a, b, and c axes are α a = 7.21 × 10 −6 , α b = 12.41 × 10 −6 , and α c = 11.50 × 10 −6 K −1 from 300 to 873 K, respectively, suggesting that Yb,Ho:GYTO possesses a small anisotropic thermal expansion IJα b /α a = 1.721) compared with GTO (α c /α a = 2.17). In addition, the thermal expansion coefficient along the a axis is smaller than those along the other directions.…”