Parasitic-free study of carrier transport in asymmetric 1.55 μm MQW laser structures

Carrier transport is supposed to be one of the major limiting processes for the high speed dynamics of SCH-MQW laser structures. It contributes to gain compression in addition to phenomena like spectral holeburning or carrier heating. The carrier transport effect also shows its influence in an RC-like rolloff of the high frequency response of laser devices. This reduction in bandwidth has been studied in the past to overcome transport problems in finding the appropriate structure, It has been proposed that it is mostly the slow transport of the heavier holes which limits the laser bandwidth. In this paper we have studied the phenomenon of carrier transport by investigating two asymmetric confined laser structures, using a parasitic-free optical modulation method. This made it possible to measure the apparent carrier transport time not only in total but for each side of the confinement layer. Finally we result in a diffusion constant for the barrier/confinement carriers in InGaAlAs material which is in good agreement with reported mobilities