AMPLIFICATION OF 26-FS, 2-TW PULSES NEAR THE GAIN-NARROWING LIMIT IN TI-SAPPHIRE

We report the generation of 26-fs-duration pulses, with an energy of 6 0 mJ, from a simple multipass Ti:sapphire amplifier system. The peak p ower of our amplified pulses is 2 TW, and the repetition rate is 10 Hz . Our amplifier design consists of two highly doped multipass amplifie rs and is simple and compact. We use an all-reflective, low-groove-den sity grating stretcher and compressor, combined with a relatively shor t material path length in the amplifier. This design allows us to mini mize higher-order dispersion. The result is a laser system that genera tes multiterrawatt transform-limited pulses, with good beam quality an d low amplified-spontaneous-emission levels, at a duration near the th eoretical limit imposed by gain narrowing in Ti:sapphire.