Design and optimization of strained-layer-multiquantum-well lasers for high-speed analog communications

We report on how the contributions from spatial hole burning, gain suppression, and relaxation oscillations to the chirp and harmonic distortion of SL-MQW DFB lasers can be calculated and minimized. It is shown how, by taking into account the specific properties of strained-layer-multiquantum-well (SL-MQW) lasers, simple solutions of the rate equations point the way to a chirp reduction and an increase of the useful bandwidth for analog communications. In such lasers, the absorption is only weakly dependent on the carrier density and therefore the harmonic distortion at lower modulation frequencies is mainly caused by spatial hole burning. Our numerical simulations indicate that in many cases this distortion is seduced by the same measures that reduce the chirp and increase the bandwidth.>