FLEXIBLE ABERRATION-FREE MULTIPASS AMPLIFIER AND COMPRESSOR FOR ULTRASHORT-PULSE AMPLIFICATION

It is shown that mode matching, aberration compensation, control of be am overlap, and feedback are critical issues in designing multipass am plifiers for ultrashort pulse amplification. We have developed a Ti:sa pphire amplifier system capable of producing aberration-free millijoul e-level 25-fs pulses at 1 kHz. This system has a unique five-mirror ri ng design, which is capable of compensating second-order aberrations, and the flexibility to mode match the input beam and the pump laser. A unique compressor, which is a part of the amplification system, was d esigned to eliminate feedback. (C) 1998 Optical Society of America.