Laser ceramics Tm:Lu2O3. Thermal, thermo-optical, and spectroscopic properties

Abstract In this paper we report the measurements of in-plane thermal diffusivity, lifetime of metastable level 3F4, thermal coefficients of linear expansion and refractive index change of laser ceramics Tm(2 at.%):Lu2O3 by the transient grating technique. The wavelengths 213, 266, 355 and 796 nm from pulsed lasers were chosen for sample excitation in accordance with the desire to measure particular parameters. The experimentally determined thermal diffusivity 0.05 cm2/s was attributed to subsurface layer, which has thickness of order of grating period. The applied approach ensured more reliable measurement of lifetime of metastable 3F4 level as compared to the conventional luminescence detection. The dynamic value of linear expansion coefficient was measured under sample excitation at 213 nm and was found to be close to that as measured elsewhere in static regime. Coefficient of refraction index change was found to be as high as 2 × 10−5 K−1. The value of absorption coefficient of ceramics at 213 nm was estimated by excitation of acoustic grating in a thin layer of air adjacent to the sample surface. After the estimation, it exceeded 104 cm−1.