<title>Exciplex pumped alkali laser (XPAL) modeling and theory</title>

Abstract

The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane, by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D2 lines provide an advantageous pathway for optically pumping atomic alkali lasers on the principal series (resonance) transitions with broad linewidth (>2 nm) semiconductor diode lasers. Because of the addition of atomic collision pairs and exciplex states, modeling of the XPAL system is more complicated than classic diode pumped alkali laser (DPAL) modeling. Results from a time-dependent finite-volume model including transport, thermal, and kinetic effects appropriate for the simulation of a cylindrical closed cell XPAL system are presented. An initial kinetic set appropriate for modeling XPAL systems is presented. A two-dimensional, time-dependent baseline simulation of an operating XPAL cell is presented and compared to data. Good agreement is achieved on the time gap between pump and laser pulses, laser pulse full width at half maximum, laser pulse rise time, and output energy. A more detailed analysis of a similar case is presented in which good agreement is obtained between laser pulse energy as a function of pump pulse absorbed energy data and predictions. Higher XPAL efficiencies are predicted as temperature increases. Initial calculations of quasi-steady-state XPAL operation, a theoretical analysis of CW XPAL systems, along with advantages over the DPAL system are also presented.