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Spectroscopic and thermal study of Er-doped oxysulfide crystal powders

The present investigation explores the upconversion properties of Er3+- doped La2O2S crystal powder as well as its potentiality for anti-Stokes cooling. A detailed study of the wavelength and pumping power dependence of the spectroscopic properties and of the temperature field of samples with various erbium concentrations is presented. The analysis of both spectroscopic and thermal measurements shows that after a transient heating induced by the background absorption, cooling can be attained by means of anti-Stokes processes.