Xenon-dimer-laser net-gain measurements

Abstract

The gain of the vacuum‐ultraviolet xenon‐dimer laser was evaluated by employing a double‐pass technique with spectral filtering of the probe radiation. At the wavelength center of the continuum‐emission spectrum (λ₀ ?1720 Å), the net‐gain coefficient at pressures less than 1.1×10⁴ Torr was found to be g₀= (1.05±0.2) ×10⁻²⁵P_s cm⁻¹, where P_s is the spontaneous‐emisssion intensity of the continuum‐emission band in units of photons/sec cm³. By comparison of laser‐output waveforms with temporally resolved net‐gain measurements, it is shown that the laser intensity is limited by an unidentified time‐dependent loss mechanism that is either foreign to the excited medium or that is driven by the laser radiation. While we do not know the source of this mechanism, our observations show that this time‐dependent loss mechanism is not associated with the lasing states of the xenon dimer. At very high pressures (≳1.3×10⁴ Torr) the effects of photoscattering by the background xenon were found to reduce the value of g₀.