50W, 50fs pulses from a fiber laser system using nonlinear fiber compression

We report on the generation of 50 fs pulses with an average output power of more than 50W. This is done by combining a high average power fiber CPA system with a microstructured large-mode-area fiber for nonlinear compression. The fiber CPA system delivers 300 fs pulses with a repetition rate of 73MHz in a linearly polarized beam with diffraction-limited quality. The average output power can exceed 100W. Nonlinear compression of these pulses is done by launching the light into a very short piece of a microstructured fiber and then removing the phase with a pair of chirped mirrors.