Aperture-Coupled Plasmonic Ring Resonator-Based Temperature Sensor: 3-D FEM Modeling

Nanophotonic ring resonators have emerged as promising candidates for sensing applications due to their high sensitivity and compact footprint. In this study, we investigated a 3-D aperture-coupled plasmonic microring resonator (AC-PMRR)-cum-plasmonic spectral shaper as a temperature sensor using finite-element method (FEM). The sensor operates based on the principle of the temperature-dependent refractive index change of the surrounding medium, which modulates the resonance characteristics of the microring. The aperture coupling technique enhances the sensitivity and allows efficient excitation of localized surface plasmon resonances. We analyzed the sensing performance of the proposed device through rigorous numerical simulations. The effects of various design parameters, such as ring radius, aperture size, and coupling distance, on the sensor's performance are systematically examined. Furthermore, we explore the influence of material properties and temperature range on the sensor's sensitivity and resolution. The proposed refractive index sensor demonstrates a high sensitivity of <tex-math notation="LaTeX">~</tex-math> 0.065 nm/K, the figure of merit of <tex-math notation="LaTeX">~</tex-math> 102 RIU <tex-math notation="LaTeX">⁻¹</tex-math> , and detection accuracy of <tex-math notation="LaTeX">~</tex-math> 0.32 nm <tex-math notation="LaTeX">⁻¹</tex-math> , making it suitable for various temperature sensing applications in fields such as environmental monitoring, biomedical diagnostics, and industrial process control.