Compression of ultrashort UV pulses in a self-defocusing gas

Compression of UV femtosecond laser pulses focused into a gas cell filled with Xe is reported numerically. With a large negative Kerr index and normal dispersion, Xe promotes temporal modulational instability (MI), which can be monitored to shorten ~100 fs pulses to robust, singly peaked waveforms exhibiting a fourfold compression factor. Combining standard MI theory with a variational approach allows us to predict the beam parameters suitable for efficient compression. At powers 30 MW, nonlinear dispersion is shown to shift the pulse temporal profile to the rear zone. ©2010 The American Physical Society