Technical Description: The goal of this project is to understand electromagnetic wave propagation in disordered photonic media and to uncover novel mechanisms that control and guide light in a new class of engineered disordered photonic band gap materials. In contrast to the conventional photonic bandgap formation theory, it has been recently predicted by the PI and her collaborators that a large isotropic complete energy gap (forbidden frequencies for all polarization), rather than a mobility gap associated with localized states, exists in certain hyperuniform disordered dielectric systems. In this research project, the PI and her laboratory bridge two areas previously considered separate: photonic bandgap, usually associated with periodicity (Bragg's scattering), and light localization, usually associated with disordered systems. They use microwave and centimeter-scale samples to uncover the nature of various electromagnetic wave modes (photonic states) in the disordered materials, measure bandgap width, robustness and dispersion, and compare their dependence on the geometry of the disordered structures to determine the properties essential for photonic bandgap formation. By exploring the functional waveguide and cavity architecture in these systems, the PI's laboratory tests these disordered bandgap structures as isotropic platforms for freeform optical circuits and demonstrates their advantages over photonic crystals in controlling photon propagation. The PI also fabricates and characterizes these disordered structures at sub-micrometer scale to explore their properties and applications in the infrared.
Non-technical Description: Photonic bandgap materials are artfully made materials designed to manipulate light propagation and have applications in many fields, including signal processing, telecommunication, lasering and solar-energy harvesting. This research project lays the experimental foundation for using isotropic disordered photonic bandgap materials for applications at microwave and infrared frequencies. The isotropic disordered photonic bandgap materials offer flexibility and versatility in device design that are prohibited by the crystalline structures in conventional photonic bandgap materials. They have a potential to advance the abilities to control and guide light and to impact the photonics industry by inventing novel photonic devices. This project integrates education and research and incorporates the research methods and results into lecture and laboratory courses at San Francisco State University (SFSU). It offers opportunities for research and career development to SFSU students and greatly enriches the learning experience of students, including large numbers of minority and economically challenged students. The PI reaches out to California educators to recruit, train, and nurture the professional development of K-12 and college teachers preparing them to integrate modern optics, materials science, and advanced geometry into their teaching, thereby enriching the education of many K-12 and college students from diverse backgrounds.
