A Highly Sensitive Metal–Insulator–Metal Ring Resonator-Based Nanophotonic Structure for Biosensing Applications

We propose and theoretically analyze an integrated biosensor scheme based on a metal–insulator–metal waveguide-coupled ring resonator structure that can be used for bio-molecular sensing applications. We incorporate silicon as a substrate, aiming that the whole structure can be fabricated monolithically in the same CMOS-compatible device. The full-field finite-difference-time-domain analysis is carried out to find the spectral response and performance characteristics of the proposed nanosensor in the NIR region of the spectrum. As the coupling of surface plasmon polaritons between two metal–dielectric interfaces of the ring increases the strength of the confined field, the sensitivity of the structure increases and reaches as high as 1383 nm/RIU. The analyses also indicate that the resonant modes can be tuned according to the design requirement keeping sensitivity almost constant. The proposed nanostructure is also investigated for some biomolecular sensing applications, and expected results are obtained.