Low-Dimensional Material-Integrated Silicon Nitride Photonic Platforms for Enhanced Light-Matter Interactions

Abstract

The ability to control light-matter interactions at the nanoscale is central to the advancement of photonic technologies relevant to information processing, sensing, and quantum technologies. Low-dimensional materials, such as monolayer transition metal dichalcogenides, provide strong excitonic and nonlinear optical responses, and are well suited for integration onto photonic structures. These materials can readily be integrated after photonic device fabrication enabling potential scalability of these systems. This thesis explores the integration of low-dimensional materials with silicon nitride photonic platforms to enhance and engineer light-matter interactions. First, silicon nitride photonic crystal nanocavities were integrated with monolayer WSe2 for investigating cavity-enhanced second-harmonic generation. By designing the fundamental mode of the cavity resonance near the excitonic resonance of the monolayer WSe2, strong enhancement of the nonlinear optical response is demonstrated compared to the bare monolayer WSe2. These results demonstrate that integrating low-dimensional materials with resonant silicon nitride photonic structures can enhance nonlinear optical processes in scalable photonic platforms. Second, several silicon nitride based photonic platforms were explored to investigate suitable structures for coupling to moiré excitons in transition metal dichalcogenide heterostructures. Optical design, fabrication, and characterization were optimized to evaluate the suitability of these resonant structures for future exciton-photon coupling investigations. These platforms provide a pathway toward integrating moiré superlattices with scalable photonic architectures for future studies of exciton-polariton formation. Finally, meta-optical resonator structures integrated with locally patterned monolayer WSe2 microdots were studied for momentum-space photonic engineering. Angle-resolved optical measurements enabled investigation of how local perturbations from the atomically thin materials can modify symmetric energy-momentum dispersion, resulting in asymmetric optical responses that depend on the microdot size and spatial position. These results demonstrate that atomically thin materials can be used to introduce localized nanoscale perturbations for engineering photonic dispersion. In summary, this thesis demonstrates the versatility of silicon nitride photonic platforms integrated with low-dimensional materials. These systems can enhance and engineer a wide range of light-matter interactions including nonlinear optical processes, exciton-photonic coupling, and dispersion engineering. These results provide a foundation for future low-dimensional material-integrated photonic devices for information processing, sensing, and quantum technologies.