Simulations of the exciplex pumped alkali laser using temperature-dependent energy pooling reactions

Abstract

Parametric measurements of pulsed output energy from the four-level Cs-Ar exciplex pumped alkali laser (XPAL) as a function of input pump energy and temperature show a strong dependence on temperature. The data shows a D2 line laser performance increase with temperature towards a peak efficiency, followed by a decrease as temperature is increased beyond the peak performance point. The efficiency was highest with Cs-Ar in the temperature range 493 – 513 K. Prior simulations of Cs-Ar XPAL measurements indicated that energy pooling from the 6p 2P3/2 state of Cs was significant at higher temperature and it was hypothesized that the addition of temperature-dependent reaction rates may be important. This paper presents BLAZE Multiphysics™ simulations using temperature-dependent energy pooling reaction rates baselined to available experimental rate data. These calculations show that the temperature-dependent energy pooling rates explain the rise and fall of Cs-Ar XPAL performance with temperature with reasonable accuracy. Longer pulse simulations are also presented that show a significant increase in optical-to-optical efficiency, but also exhibit a faster decay at higher cell temperatures due to the increased impact from energy pooling. Estimates of temperature-dependent energy pooling reaction rates are presented for Rb and K.