Frequency chirp reduction in a 2.2 Gbit/s directly modulated InGaAsP semiconductor laser by CW injection

Longitudinal-mode linewidth broadening due to frequency chirping in a high-speed modulated InGaAsP laser transmitter is reduced by CW injection of a master laser with a matched longitudinal mode. Biased below threshold and modulated with RZ format 2.2 Gbit/s current pulses, the transmitter laser's frequency chirp can be reduced at the expense of a small pulsewidth increase and on/off ratio reduction.