Abstract

An important issue associated with amplifying subpicosecond pulses is the presence of nonlinear effects in the amplifying medium. In this respect gas amplifiers have the advantages of a smaller nonlinear index of refraction than dye or solid-state amplifiers and a scalability to larger apertures. In addition, the XeF(C → A) excimer amplifier in the blue-green spectral region is an ideal subpicosecond amplifier because of its broad bandwidth and saturation energy densities about 40 times greater than conventional UV excimers.¹ It has been used to amplify subpicosecond pulses to the terawatt power level. In this paper we report the self-focusing of a subpicosecond laser beam, in a XeF(C → A) excimer amplifier for output energy densities exceeding 100 mJ/cm² and show the design of a multipass resonator for optimal energy extraction that avoids self-focusing.

© 1991 Optical Society of America