Experiments on QD lasers grown on GaAs and on Si have revealed the quenching of the GS optical power as the current overcomes the ES threshold. A common technique to mitigate this quenching is the modulation p-doping, but an excessive p-doping level results in a deterioration of the GS optical power and threshold current. Theoretical models based on rate equations have ascribed the GS power quenching to the de-synchronization between the electron and hole dynamics. However, these approaches resort to phenomenological transport times. In this contribution, we study a 1.3 um QD laser grown on silicon by employing a drift-diffusion model for the transport of carriers across the SCH region. We show that the unbalance of electron and hole mobilities in the GaAs barriers is responsible for the GS quenching. The simulations also emphasize the existence of an optimum modulation p-doping level minimizing the GS threshold current, which we ascribe to electrostatic effects induced by this doping.
By applying a recently proposed coupled-Bloch-mode approach, we have derived the resonance condition for the longitudinal modes of passive photonic crystal (PhC) line-defect cavities. We have derived simple expressions for the electric field depending on the size of the cavity and the order of the resonant mode. We have shown that, as the cavity becomes longer, the fundamental mode turns from FP-like to DFB-like and the fraction of its wavevector components within the light cone is gradually suppressed. Importantly, we have clarified the physical origin for this behaviour.