Chirped-Disordered Topological Nanophotonic Resonator for Improved Electric Field Confinement

In this manuscript, a disordered topological nanophotonic resonator structure has been proposed for improved electric field confinement. The topological effect is realized by connecting two photonic crystal (PhC) structures having overlapping bandgaps and opposite Zak phase. Further, an exponential graded refractive index profile is used to modify the dispersion characteristic of the device. This results in the confinement of a topological edge state at 1546nm wavelength. The structural performance is compared with the conventional step-index resonator and step-index topological resonator. The topological structure shows a 136% higher electric field intensity of confined resonating mode. The proposed graded topological structure results in a 135% higher average sensitivity than the conventional FP-cavity structure and 24% higher than the step-index topological structure.