Effect of semiconductor nonlinear gain on the chirpand spectral properties of amplified subpicosecond optical pulses

The properties of optical pulse chirp and spectra from semiconductor optical amplifiers have been studied numerically for subpicosecond input optical pulses. It is found, in accordance with experimental results, that owing to the effect of nonlinear gain, positive chirp can occur in the trailing edge of the output pulse, and the corresponding spectrum is composed of two dominant peaks. These calculations provide the first theoretical explanation of these experimental measurements.