Effects of rare gas collision partner and pump energy on the four-level Cs exciplex pumped alkali laser

Abstract

Experiments operating a Cs D2 line (852.1 nm: 62P3/2→62S1/2) laser, pumped by blue wing absorption of different thermal Cs-rare gas ground state pairs, were analyzed. Using a 10 cm sealed gas cell, the D2 line laser performance is highest for Cs-Ar at 513K, and for Cs-Kr and Cs-Xe at 473 K. Overall, the highest optical-to-optical efficiency measured was 1.1% with a linear slope efficiency of 1.5% for the Cs-Ar collision pair at 513 K. All three Cs-rare gas mixtures show 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. At lower temperatures ≤453 K the efficiency was highest with Cs-Xe, at 473 K highest with Cs-Kr, whereas at higher temperatures ≥ 493 K the efficiency was highest with Cs-Ar. Measurement of the reduced absorption coefficient for the peak of the blue satellite of the different collision pairs resulted in values of 1.2∙10-36 cm5 for Cs-Ar at 836.7 nm, 2.0∙10-36 cm5 for Cs-Kr at 841.1 nm, and 3.0∙10-36 cm5 for Cs-Xe at 842.7 nm. Simulations of the data using the detailed BLAZE Multiphysics software suite were also performed, which aid in the understanding of the basic physics behind the XPAL system. The simulations indicate that energy pooling significantly inhibits laser performance at higher temperatures above 500 K.