Mode-locking of long-pulse XeF and KrF lasers

Active-locking of 1 to 2 microsec KrF and XeF e-beam pumped oscillators has been demonstrated. Fundamental and harmonic mode-locking were performed. Individual pulse widths were approximately 1 ns full width at half maximum (FWHM). The pulses were much wider than the theoretical limit. This was caused by mechanical instability, and the difficulties of reproducing an exact cavity length of a large, single shot device. Under certain conditions, the changing index of refraction of the laser medium led to further pulse lengthening.