Femtosecond watt-level fiber amplification circuits

Direct amplification of femtosecond optical pulses in single-mode fibers is limited to subnanojoule output energies. This limitation, which is due to strong nonlinear effects at high peak intensities, can be substantially alleviated by resorting to the chirped pulse amplification (CPA) method. Different CPA "circuit" configurations have been demonstrated employing single or double gratings for femtosecond pulse stretching and recompression. These implementations have revealed that, apart from compactness and robustness, the other essential property of a chirped Bragg-grating stretcher/compressor is the reciprocity of the temporal delay characteristics. This eliminates the necessity to adjust higher-order phase mismatch between the stretcher and compressor for generating bandwidth-limited femtosecond pulses.