The gain characteristics of an electron-beam pumped XeF(C-+ A) excimer amplifier operating in the bluegreen spectral region were investigated for several laser pulse lengths. Saturation energy densities of 50 and 80 mJ/cm2 were measured for injected laser pulse durations of 250 fs and-100 ps, respectively. A gain bandwidth of 60 nm was observed with-100 ps pulse injection. Using an optimized unstable resonator design, the laser amplifier has produced 275 mJ pulses with a pulse duration of 250 fs and a 2.5 times diffraction limited beam quality, making the XeF(C-+ A) amplifier the first compact laser system in the visible spectral region to reach peak powers at the terawatt level.

Analysis of a combination zone plate and lens system is presented for the design of optical systems to focus ultrashort laser pulses. A system design that is free of propagation-time delay distortion and chromatic aberration is presented.

Tunable blue-green subpicosecond laser pulses have been amplified in an electron-beam-pumped XeF(C --> A) excimer amplifier. Small-signal gains of 3.5% cm(-1) were measured using a 50-cm active gain length. At output energy densities as high as 170 mJ/cm(2), only a small degree of saturation occurred, resulting in a gain of 2.5% cm(-1).

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The expansion of a laser-produced Be plasma is studied by comparing hydrodynamical model calculations with experimentally measured distributions of each charge state as a function of energy. The plasma is generated with 1–10-J 200-ps pulses from the LPARL Nd-glass laser facility, and the distributions are obtained using a Thomson parabolic spectrograph. The hydrodynamic equations include flux-limited thermal conductivity and collisional-radiative recombination and ionization. For the proper choice of the initial parameters, we obtain qualitative agreement between the model prediction and the experimentally measured distributions.