Computer Simulations of Photonic Semiconductor Devices
Doctoral thesis, 1992
This thesis aims to provide insight into three important aspects of modern computer simulation techniques related to advanced photonic semiconductor devices. These aspects are quantum size effects, waveguiding properties, and device dynamics. The quantum size effects are prominent in devices fabricated using modern growth techniques by which thicknesses of only a few atomic layers can be achieved. A fast and efficient algorithm for solving the one-dimensional time-independent Schrödinger equation is a key tool for the understanding of these devices. It is shown that the transfer matrix method is a good choice for these simulations and the method has been implemented to calculate the location of the energy levels and wavefunctions for many types of potential profiles. It is also shown that the algorithm implemented is capable of handling not only bound states but also quasi-bound energy states in complicated potential profiles. Furthermore, the transfer matrix method is demonstrated to be an effective tool for calculating the propagation characteristics of one-dimensional slab waveguides. Calculation of the optical field is a prerequisite for investigations of coupling in waveguides. The propagation constants and optical field can be calculated for both real and complex refractive indices, which makes it possible to analyze structures with both loss and gain. The thesis also deals with the problem of simulating the dynamic behavior of a twin-electrode semiconductor laser. A simple and efficient algorithm is implemented, based on the traveling-wave rate-equations. This is used to simulate optical picosecond pulse generation through active Q-switching. All these methods have been implemented on a small single-user computer. While most computer models existing today are especially designed for solving a specific type of problem, the key feature of the models presented in this work is the capability to simulate nonuniform semiconductor structures over a wide span of applications. For each model presented, a special effort has been made to verify the performance by comparison with experimental results. The methods described are found to be fast and accurate when compared with results obtained by more advanced methods. In conclusion, this work enables computer simulation to become a practical design aid in the development of many different types of advanced photonic devices.
quantum size effects
transfer matrix method