Excitation of higher lying states in a potassium diode-pumped alkali laser

Abstract

A kinetic model for the performance of a potassium DPAL, including the role of higher lying states, is developed to assess the impact on device efficiency and performance. A rate package for a nine-level kinetic model including recommended rate parameters is solved under steady-state conditions. Energy pooling and far wing absorption populates higher lying states, with single photon and Penning ionization leading to modest potassium dimer ion concentrations. The fraction of the population removed from the basic three levels associated with the standard model is less than 10% for all reasonable laser conditions, including pump intensities up to 100 kW cm $$^{-2}$$ and K densities as high as $$10^{16}$$ cm $$^{-3}$$ . The influence of these effects can largely be mitigated by proper control of the inlet alkali density.