Direct femtosecond pulse compression with miniature-sized Bragg cholesteric liquid crystal.

Direct compression of femtosecond optical pulses from a Ti:sapphire laser oscillator was realized with a cholesteric liquid crystal acting as a nonlinear 1D periodic Bragg grating. With a 6 μm thick sample, the pulse duration could be compressed from 100 to 48 fs. Coupled-mode equations for forward and backward waves were employed to simulate the dynamics therein, and good agreement between theory and experiment was obtained.