Contribution of dissolved platinum ions to heat dissipation in ytterbium–erbium glass under lamp pumping

Abstract

Subject of study. The contribution of platinum ions dissolved in ytterbium–erbium phosphate glasses to the heating of active elements under lamp pumping is investigated in this study. Laser-quality glasses are synthesized in platinum crucibles; therefore, they always contain a certain amount of platinum depending on many factors. One of these factors is the duration of the melting process, which for erbium glasses is two or more times longer than that for neodymium glasses. This results in an elevated platinum content in the former. Methodand brief description of the experiement. Heat dissipation in an active element was determined using its relative elongation during the propagation of a pumping pulse. The elongation was obtained using an interferometric method. Glasses with different platinum contents were melted to determine the contribution of platinum ions to the overall heat dissipation of the active element. Experimental dependences of the platinum ion contribution to the overall heat dissipation on the concentration of platinum ions in LGS-KhCh glass (V. A. Kotel’nikov FIRE RAS) were obtained for active elements with sizes of ∅4×80mm. We established that up to 10% of the overall heat is generated in the absorption bands of the platinum ions in the active elements made of glass with a passive loss level corresponding to laser applications. The obtained data made it possible to explain the previously observed discrepancies between experimental data and the calculation results using a model of ytterbium–erbium and chromium–ytterbium–erbium active media proposed by the authors. The practical significance of this study is a recommendation of additional filtering of the pumping lamp radiation to reduce the heating of active elements formed of ytterbium–erbium glasses.