Accurate Characterization of the Properties of the Rare-Earth-Doped Crystal for Laser Cooling

摘要

We present a method for calibrating a commercial thermal camera adopted to accurately measure the temperature change of the sample in a laser-induced temperature modulation spectrum (LITMoS) test, which is adopted for measuring two crucial parameters of the external quantum efficiency eta(ext) and the background absorption coefficient alpha(b) for assessing the laser cooling grade of the rare-earth-doped materials. After calibration, the temperature resolution of the calibrated thermal camera is better than 0.1 K. For the cooling grade Czochralski-grown 5% Yb3+:LuLiF4 crystal, the corresponding values of eta(ext) and alpha(b) are LITMoS = measured to be eta(ext )= 99.4 (+/- 0.1)% and alpha(b )= 1.5 (+/- 0.1) x 10(-4) cm(-1), respectively.

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