Hot carrier and hot phonon effects on high-speed quantum well lasers

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Abstract
We present a theoretical model to analyze the hot carrier and hot phonon effect on the modulation response of semiconductor quantum well lasers. We find that the carrier heating strongly depends on the energy relaxation time of carriers and the lifetime of longitudinal-optic (LO) phonons. Furthermore, the carrier heating will significantly decrease the differential gain and increase the nonlinear gain coefficient and thus reduce the modulation bandwidth. From the numerical result, we demonstrate the bottleneck effect of the hot LO phonons on the modulation response of quantum well lasers. This implies that reducing the lifetime of LO phonons, for example, by doping in the quantum well, will most effectively decrease the carrier temperature and thus improve the modulation bandwidth.