Transient absorption and its influence on energy extraction in a discharge-pumped F₂ laser

Small-signal transient absorption of a discharge-pumped F₂ laser (157.6 nm) medium was measured by using a Raman-shifted F₂ laser (168.6 nm). The small-signal total absorption was obtained for 6 atm laser media at an excitation rate of ∼26 MW/cm³, where a small-signal net gain was independently measured to ∼35%/cm, as the sum of a transient absorption of ∼2.5%/cm and a stationary absorption of ∼0.5%/cm. In spite of the relatively large gain-to-loss ratio a significantly low maximum laser intensity of ∼2 MW/cm², which gives zero extraction efficiency in the F₂ laser medium, measured in heavily saturated F₂ laser amplification experiments, suggests that the energy extraction is limited by additional absorption.