SIMULTANEOUS AMPLIFICATION AND COMPRESSION OF PICOSECOND OPTICAL PULSES DURING RAMAN AMPLIFICATION IN OPTICAL FIBERS

A novel technique that can lead to simultaneous amplification and compression of picosecond optical pulses is proposed. It consists of copropagating a weak signal pulse with an intense pump pulse in an optical fiber whose minimum-dispersion wavelength is chosen such that it falls between the pump and the signal wavelengths. The pump pulse amplifies the signal pulse through stimulated Raman scattering and at the same time imposes a nearly linear frequency chirp on it through cross-phase modulation. The chirped signal pulse is simultaneously compressed in the anomalous-dispersion regime of the optical fiber as it becomes amplified. Numerical simulations are used to predict the extent of amplification and compression under realistic practical conditions. The signal pulse can be compressed by more than a factor of 10 while it is amplified by 40-50 dB.