XPAL modeling and theory

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. The BLAZE-V model is utilized for high-fidelity simulations. BLAZE-V is a time-dependent finite-volume model including transport, thermal, and kinetic effects appropriate for the simulation of a cylindrical closed cell XPAL system. The model is also regularly used for flowing gas laser simulations and is easily adapted for DPAL. High fidelity calculations of pulsed XPAL operation as a function of temperature and pressure are presented along with a theoretical analysis of requirements for optical transparency in XPAL systems. The detailed modeling predicts higher XPAL performance as the rare gas pressure increases, and that higher output powers are obtainable with higher temperature. The theoretical model indicates that the choice of alkali and rare gas mixture can significantly impact the required intensities for optical transparency.