CARRIER DC AND AC CAPTURE AND ESCAPE TIMES IN QUANTUM-WELL LASERS

A theoretical model is proposed to study the carrier de and ac capture and escape times in the small signal modulation response of quantum-w ell lasers. We derive the de and ac capture and escape times by calcul ating the carrier net capture current. Our numerical results indicate that the ac capture and escape times are smaller than the de capture a nd escape times. In some cases, they may be even smaller by one order of magnitude. We also find that the ac capture/escape time ratio is la rger than the de capture/escape time ratio by a factor of two. Therefo re, conventional theoretical models that do not distinguish the differ ences between the de and ac capture and escape times may overestimate the resonant frequency and underestimate the damping rate in the modul ation response of quantum-well lasers, i.e., the ac capture and escape times limit the modulation bandwidth of quantum-well lasers more seve rely than that predicted by the de capture and escape times.