Carrier capture delay and modulation bandwidth in an edge-emitting quantum dot laser

We show that the carrier capture from the optical confinement layer into quantum dots (QDs) can strongly limit the modulation bandwidth omega(-3) dB of a QD laser. As a function of the cross-section sigma(n) of carrier capture into a QD, omega(-3) dB asymptotically approaches its highest value when sigma(n) -> infinity the case of instantaneous capture). With reducing sigma(n), omega(-3) dB decreases and becomes zero at a certain nonvanishing sigma(n)(min). The use of multiple-layers with QDs significantly improves the laser modulation response-omega(-3) dB is considerably higher in a multilayer structure as compared to a single-layer structure at the same dc current. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3571295]