Critical Microscopic Processes in Semiconductor Lasers

Operation of semiconductor laser diodes with multiple quantum wells in the active region depends on several critical microscopic processes. These include capture of carriers into the quantum wells, cooling of the injected carriers, non-radiative recombination of carriers in the quantum wells and the optical gain in the quantum wells which leads to stimulated emission. Each of these processes presents a fundamental challenge for theoretical analysis. Furthermore, experiments prove a non-trivial combination of these processes. An integrated laser simulator has been developed which includes carrier transport, quantum mechanical treatment of the quantum wells and the optical field in a self consistent analysis of the laser diode. The simulator allows direct comparison to experimental data and analysis of the impact of the various microscopic processes on the operation of the laser diode. For example, an accurate model for the optical gain, including a proper treatment of the broadening, must be combined with the details of the transport of carriers through the multiple quantum well region to understand the measured optical spectra.