Abstract

Use of the chirped pulse amplification 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, high contrast pulses. We report here several techniques for generating subpicosecond pulses at 1.053 µm with ultrahigh contrast. One of the disadvantages of the fiber grating compression technique is that the rectangular shape of the spectrum requires 30-cm^–1 bandwidth to generate a picosecond pulse. Also, a sine² pulse shape results with a few percent of the pulse energy contained in pre- and postpulses. A carefully designed Nd:phosphate glass regenerative amplifier has successfully been utilized to shape the spectrum of the chirped pulse to a near-Gaussian profile. Multiterawatt transform-limited pulses of ≈0.9-ps duration and 22-cm^–1 bandwidth have been obtained with an intensity contrast ratio >10⁵:1.

© 1989 Optical Society of America