The objective of this research is to demonstrate monolithic integration of magneto-optical isolators on semiconductor substrates and to characterize their performance. The approach is based on developing a nonreciprocal resonant optical cavity device using monolithically grown polycrystalline cerium-yttrium-iron-garnet as the magneto-optical medium, and new photosensitive chalcogenide glass materials for robust post-fabrication trimming. The research will leverage gray-scale processing technologies and high-order Fano resonant cavity architectures to realize record-breaking device performance. The intellectual merit of this work is the combination of new materials and innovative device designs. Prior on-chip isolators have largely relied on wafer bonding of magneto-optical garnets, traditionally considered incompatible with monolithic integration on semiconductors. The proposed work will combine new growth methods and materials with new device designs to simultaneously achieve monolithic integration, passive device operation, large isolation ratio, minimal insertion loss, small footprint, as well as superior fabrication tolerance, thus resolving the standing challenge of efficient on-chip optical isolation. The broader impacts of this work include its potentially transformative impact on the field of optical communications and photonic signal processing by providing the first practical solution for monolithic on-chip isolation. When the number of components in a photonic chip increases, parasitic reflections between components can seriously jeopardize circuit functionalities by destabilizing laser and circuitry operation. The need for on-chip isolation therefore becomes imperative as the level of photonic integration continues to scale. The scientific research will be tightly integrated with graduate course development, undergraduate training, and development of hands-on modules for K-12 classrooms at both institutes.
