Performance analysis of hyperbolic graded topological resonator for biosensing applications

In this manuscript, a novel hyperbolic-graded nano-photonic resonator structure based on the photonic crystal is proposed for biosensing applications. The graded refractive index is realized by considering a porous silicon material having a deliberately modulated local refractive index. The introduction of grading effectively modifies its dispersion characteristics. These crystals exhibit overlapping bandgaps and opposite Zak phases, enabling the manifestation of unique topological properties. The design parameters are optimized to excite a topological edge state at a 1521 nm operating wavelength, whereas a resonating TES is excited at a 1533 nm. The structure performance is analyzed using the finite element method. The analytical results exhibit an improved sensitivity of 1806 nm/RIU (refractive index unit) and a Figure of Merit (FOM) of 4030 RIU⁻¹, which are 151% and 2483% higher than recently reported values. With its remarkable performance metrics, the proposed device holds significant promise for accurately detecting and sensing biochemical samples with very high efficiency.