Modeling, simulation and design techniques for high-density complex photonic integrated devices and circuits

High-density photonic integration based on the high-contrast optical waveguide structures has become increasingly appealing for realizing multi-functional photonic circuits of compact size. In the meanwhile, accurate and efficient modeling, simulation and design of such devices and circuits become increasingly challenging. Effects such as the vector nature of the fields, the reflection at waveguide junctions, and enhanced optical nonlinearity, etc., need to be considered. The main objectives of the research for this thesis are to investigate and develop novel numerical techniques that are suitable for modeling and simulation of waveguide structures made of high index contrasts and with complex structures.; After an introduction, the thesis first describes several methods for computation of complex modes that exist in bending and anti-guiding optical waveguides. A cylindrical perfected matched layer (CPML) is first introduced and applied in computing the full-vectorial complex modes in cylindrical system. Subsequently, two powerful methods are proposed to handle multiple modes of leaky structures. The methods utilize the transverse resonance when a signal propagates along the waveguide. The "information" stored in the output signal is extracted by well-established digital signal processing technique and converted into the modal parameters. Theoretically, the new methods can compute all modes by post-processing the information stored in the output signal.; Then the thesis devotes itself to the light wave propagation in and interaction with optical waveguide structures. Aim at handling high-density complex photonic integrated devices, various methods and algorithms have been developed to simulate the light wave propagation and scattering in both frequency and time domains. The main feature of these methods is that they are attempting to solve the complex problems by combining different approaches. Since those individual approaches are especially good at dealing with one particular problem, the combination, therefore, can significantly extend their applications in much wider range. The efficiency and accuracy of the proposed methods have been verified and demonstrated by various photonic integrated devices.; Finally, the space mapping (SM) technique is introduced for the design and modeling of optical devices. This technique provides a unique way to let computational intensive models, such as finite difference time domain (FDTD) method, play an important role in design optimization and modeling. Remarkable designs have been achieved in only several FDTD simulations.