Design of vertical cavity surface-emitting lasers with strained and unstrained quantum well active regions.

摘要

The dissertation can be divided into three main topics. The first part will tackle issues related to the calculation of optical gain in strained and unstrained quantum wells in the InGaAs/AlGaAs system. A detailed account of the gain model and the method of solution of the valence band Hamiltonian will be presented. The primary interest here is in determining how the optical gain characteristics vary with indium content in the well, barrier height, well width, and modulation doping.;The second part of the dissertation considers issues related to the design of vertical-cavity surface-emitting lasers (VCSELs). The approach developed here uses a normalized family of curves defined by a single normalization parameter to describe the light versus current characteristics of the laser. Optimization of the laser design then involves simply minimizing this one parameter. An accurate description of the entire laser cavity including the mirrors, internal losses, and gain will be provided in order to evaluate and compare the normalization parameter for various cavity designs. A fundamental description of the laser cavity using Maxwell's equations will also be included to highlight the concept of volume confinement factor and its importance in the description of standing wave effects.;The third and final part of the dissertation involves the use of optical pumping techniques for the characterization of VCSELs. General considerations and requirements will first be examined. Initial experiments on periodic gain active region VCSELs will then be presented. Thermal effects related to the optical pumping of VCSELs will be discussed and shown to be important in the interpretation of quasi-continuous wave optical pumping measurements. Finally, example measurements on present-day VCSEL designs in both unstrained GaAs and strained InGaAs QW VCSELs will be presented.