Modeling and simulation of optically pumped micro-cavity semiconductor laser structures.

摘要

Micro-cavity lasers are defined as lasers with optical cavities whose sizes are comparable to the wavelength of light in the material. For practical semiconductor materials with relatively large indices of refraction (n > 3.0), these sizes turn out to be in the tens to hundreds of nanometer range. The micro-cavities are considered to be promising candidates for future integrated photonic circuitry. Over the past decade, many prototypes of semiconductor micro-cavity lasers have been demonstrated, and many innovative designs continue to be intensively investigated.; This Ph.D. thesis work focuses on the development of a framework for the numerical modeling and simulation, and the theoretical study of existing and future promising micro-cavity laser structures. The simulation illustrations use optically-pumped micro-lasers. The framework uses a coupled optical and electronic approach, which involves the simultaneous solution of the semiconductor device equations and the photon rate equations. Furthermore, it includes the modification of spontaneous emission by the unusual micro-cavity effect. To deal with arbitrary device geometries, a full-wave finite-difference time-domain (FDTD) solver is also developed to follow the evolution of optical field in the structure.; Four sets of micro-cavity laser structures have been investigated in this thesis work. Initially, we carry out complete numerical simulations of GaN nanowire lasers, and two-dimensional single defect photonic crystal slab lasers. Many critical characteristics are studied. These include optical properties, spontaneous emission, stimulated emission, output light versus pumping carrier density rate, and lasing spectra. Looking into the future, we also propose and simulate two innovative device types: a nanowire superlattice laser with distributed Bragg mirrors, and a novel electrically-pumped single defect photonic crystal laser. Through these studies, we have demonstrated the applicability of our framework for the simulation of existing and new microlaser device structures.; Finally, we conclude by suggesting several extensions to our simulation framework, and by pointing the way to other future micro-cavity laser structures.