| dc.description.abstract | Optical signal processing is a crucial field for meeting our growing information needs, finding use for example in fiber optics for long-haul telecommunications. There is currently an aim to bring optical technologies closer and closer to the chip where information is processed, potentially allowing for more energy-efficient and higher-bandwidth signal processing. Photonic crystals (PhCs), engineered media that exhibit photonic band gaps, can be designed to produce resonant optical cavities, and the operation of these PhC cavities provides a versatile platform for the creation of nanoscale optical modulators to encode and decode signals with light. In this dissertation, design strategies for silicon PhC cavities are investigated in order to establish techniques for optimizing the performance and functionality of these devices within optical modulators. First, the use of a bus waveguide, side-coupled to a PhC cavity, is demonstrated to enable high-transmission, high-quality-factor resonance, giving rise to a novel PhC cavity design with uniform mirrors. In addition, a methodology is developed for combining different unit cell geometries into a single PhC cavity, which allows for non-traditional unit cell shapes with specific functionality to be included with minimal impact on quality factor, such as the “bowtie” for enhanced light-matter interaction. Following these design advances, applications of these PhC cavities are then explored for use in optical modulators. A hybrid Si-VO2 PhC cavity platform for optical modulation is designed and simulated by carefully incorporating the phase change material VO2 onto a PhC to control the wavelength and quality factor of its resonance, and thereby achieve a simulated modulation depth of 10 dB. Additionally, a bowtie PhC cavity geometry is investigated for all-optical switching, motivated by the potential of the high peak energy density of the bowtie shape to enhance nonlinear optical processes in silicon. PhCs are, therefore, envisioned as a building block for components of photonic integrated circuits, and their use in resonant cavities has applications in next-generation optical switching. | |
