Experimental and numerical investigation of thermal effects inend-pumped Cr4+:forsterite lasers near room temperature

摘要

The results of a study which employs both experimental andntheoretical methods to investigate the role of thermal effects innroom-temperature Cr4+:forsterite lasers are presented. Annovel model was developed to calculate the incident threshold pump powernrequired to attain oscillation by taking into account absorptionnsaturation and pump-induced thermal loading in the gain medium.nExperimentally, the incident threshold pump power was measured as anfunction of the crystal boundary temperature for threenCr4+:forsterite laser crystals with different small-signalndifferential absorption coefficients Αp0 and/orncross-sectional areas. Excellent agreement was obtained between theorynand experiment for values of the stimulated emission cross sectionncomparable to those from previously reported data. The model was thennused to numerically determine the optimum value of Αp0nwhich minimizes the incident threshold pump power in room-temperature Crn4+:forsterite lasers. At a crystal boundary temperature ofn15°C, the optimum value of Αp0 was determined to ben0.64 cm-1 for a 2-cm-long Cr4+:forsterite crystal,ncorresponding to an unsaturated absorption of 72%. The use of crystalsnwith an optimum absorption coefficient should lead to the realization ofnhighly efficient CW Cr4+:forsterite lasers at roomntemperature