Abstract

We recently demonstrated the production of over a petawatt of peak power in the Nova/Petawatt Laser Facility, generating > in < 500 fs. The Petawatt Laser Project was initiated to develop the capability to test the fast ignitor concept¹ for inertial confinement fusion (ICF), and to provide a unique capability in high energy density physics. The laser was designed to produce near kJ pulses with a pulse duration adjustable between 0.5 and 20 ps. The laser system begins with a Ti:sapphire chirped pulse amplification system operating at 1054 nm. The pulse is stretched to ~ 3 ns and is amplified up to 50 mJ in the titanium-sapphire section with minimal bandwidth narrowing. Further amplification in mixed phosphate glass amplifiers produces a spectrally-shaped pulse at near kilojoule levels. Only the central 80% of the disk amplifiers is utilized in order to maintain a good wavefront, and near diffraction limited beam quality should be possible with the use of a deformable mirror wavefront correction system to correct for static and thermal and pump-induced aberrations in the amplifier chain. Following amplification, the chirped pulse is compressed to 0.43 - 20 ps by a pair of 94-cm diameter diffraction gratings arranged in a single pass geometry. Pulse compression occurs in vacuum with a compressor throughput of 75%. These large aperture gratings enable the production of petawatt pulses with > 900 J.

© 1998 IEEE