The use of the chirped pulse amplification (CPA) technique1 in large Nd:glass based amplifier systems is rapidly making possible focused intensities in the 1017-1019-W/cm2 range, allowing a variety of experiments to be performed in a fundamentally new regime. Many of these experiments require not only high peak intensities but also clean very high contrast pulses. Previously it was shown that high contrast subpicosecond amplified pulses at 1.053 μm can be obtained when gain narrowing and spectral modulations from the amplifiers are sufficiently reduced.2 Gain narrowing is minimized when the net gain approaches the total amplifier gain. This is achieved only in very low loss amplifier systems. Spectral modulation arising from etalon effects or (thermal and static) birefringence must also be avoided by keeping the number of optical surfaces and path lengths transmitted to a minimum.
© 1990 Optical Society of AmericaPDF Article