Chirp control of an optical signal using phase modulation in a semiconductor optical amplifier

We demonstrate that phase modulation in a semiconductor optical amplifier converts a positively chirped signal launched from an electroabsorption modulator into negative chirp. This negative chirp reduces the broadening of optical signal waveform due to the anomalous dispersion in standard single-mode fiber (SMF). A 2.5-Gb/s transmission experiment across 600-km SMF confirms that the chirp control technique is effective for extending the signal transport distance.