Transport-limited modulation bandwidth of quantum well, wire, and dot lasers

Recently, it was shown that transport effects, including both diffusion in the separate confinement (SCH) region and intrinsic capture of carriers into the quantum well (QW), are significant in determining the ultimate modulation bandwidth of QW lasers.1-3 In particular, it was shown that the intrinsic quantum capture process, which has a subpicosecond time scale and, therefore, was considered to be irrelevant to the modulation response, even at 100 GHz, does indeed matter a great deal.3 In this paper we offer a simple physical interpretation of the quantum capture effect and, by inference, predict the ultimate modulation-bandwidth limit of various quantum wire and dot laser structures.