XeCl Laser Power Enhancement with an External Ultraviolet Laser

Enhancements in the output energy of an XeCl laser of more than 50 percent have been observed by Injecting 2–43 mJ of 308 nm laser radiation into the resonator 10–150 ns prior to the emergence of the final XeCl pulse. This effect is a strong function of the time delay (Δt) between the two lasers and is most pronounced when the injected (external) pulse precedes the XeCl laser pulse by 45 ns. For| Δt| ≤ 100 ns, the external radiation appears to be simply “seeding” the XeCl laser cavity which allows the second laser to reach threshold earlier and thereby improve its extraction efficiency. For 100 ≤ |Δt| ≤ 150 ns, the enhancement may to arise from the depletion of the number density of an impurity molecule which absorbs strongly at 308 nm.