Intrinsic, P-Doped and Modulation-Doped Quantum Well Lasers for UltrafastModulation and Ultrashort Pulses

摘要

This contract studied experimentally and theoretically the fundamental limit inthe modulation bandwidth of quantum well lasers. The motivation of this study arises from the fact that, despite numerous predictions in the last few years on the potential superiority of quantum well lasers in high speed modulation, none of them have been successfully verified experimentally. The initial approach was to study gain compression as a fundamental mechanism of limiting modulation bandwidths of quantum well lasers. To the extent that the physics behind gain compression was not known, a major effort was put in uncovering the fundamental physics responsible for gain compression. It was subsequently discovered that the finite carrier capture time into the quantum well, despite being a very fast process (1 ps or less), can lead to a large gain compression parameter. We have then proceeded along this line and studied the fundamental quantum capture of electrons and holes into quantum wells, as well as the consequence of these capture processes in the modulation dynamics of quantum well lasers. The goal here is not only to understand what limits the modulation bandwidth of quantum well lasers, but to make use of that knowledge to design suitable structures for overcoming these limitations. The following sections contain detailed descriptions of the experimental and theoretical work that uncovered the above facts.