SIMULATION AND CHARACTERIZATION OF QUANTUM WELL VERTICAL CAVITY SURFACE EMITTING LASERS

Abstract

Vertical cavity surface emitting lasers or VCSELs are the preferred light source for fiber-optic communication in the industry. In this study, a VCSEL containing the AlGaAs/GaAs quantum well structure as the active material is analyzed both theoretically and experimentally. The quantized energy states, energy-momentum dispersion and bandstructure is computed by solving Schrödinger’s equation in 1D accounting for band nonparabolicity using an approximation of the Luttinger-Kohn Hamiltonian. For a given injected carrier concentration and temperature, the material gain spectrum, transparency condition and device threshold current is estimated. With this set of simulation tools, an optimum quantum well structure is investigated by varying well width, barrier composition as well as the number of quantum wells. A modified quantum well structure is proposed for better performance over a wider range of temperatures. The simulation is verified using data from low and room temperature photoluminescence as well as experimentally obtaining the material gain spectrum using the Hakki-Paoli technique.