Computer program for the kinetics and populations in a xenon fluoride laser

Abstract

To highlight in a qualitative manner the kinetics of an excimer laser, a simple computer model for calculating the species populations in a KrF laser cavity is developed; subsequently a computer program originally developed at the Naval Research Laboratory (NRL) is modified to calculate the population of different electronic configurations of excited neon present in a XeF laser. When modified, the NRL program accounts for 185 reactions and requires 9.5 minutes of CPU time using the IBM 360-67. The populations obtained are applied to the calculation of the index of refraction in the laser cavity. the phase shift is determined per unit length for the two laser wavelengths; one laser wavelength is non-resonance with neon and the other is at resonance. Neon is the dominant specie relative to concentration and within the population distribution the neon ground state dominates by a factor of a million. The calculations show that the ground state neon determines the index of refraction; an exception occurs if the laser wavelength is near resonance to any of the transitions in the 3s . 4p array. As long as the laser is operated away from the 3s > 4p resonant wave-lengths, the phase shift will be negligibly small resulting in satisfactory beam quality; the preceding statement is valid only for the influence of neon.