High sensitivity plasmonic refractive index sensor for early anaemia detection

Plasmonics is gaining prominence in the area of optical sensing due to the unique way that noble metals and light interact to produce subwavelength confinement. A Metal Insulator Metal waveguide based plasmonic nanosensor exhibiting multi Fano resonance is proposed. The characteristics of transmittance of the proposed sensor are investigated using the Finite Difference Time Domain methodology. Three Fano resonances can be seen in the transmission characteristic with different sensitivities of 992.4 nm/RIU, 1294.8 nm/RIU and 2065.5 nm/RIU at 1.0257 μm, 1.3239 μm and 2.0798 μm respectively. Furthermore, the sensor performance is investigated for potential fabrication issues arising out of variation in structural parameters such as the coupling distance and the radius (both inner and outer) of the semi-ring arc resonator. The performance of the sensor is also assessed for performance metrics like the Figure of Merit (FOM), Q factor, and Detection Limit, which are obtained as 39.7 RIU⁻¹, 39.9 and 0.025 respectively. The characteristics of the Fano resonances obtained through simulation is also validated by matching it with the theoretical Fano line shape function. The proposed sensor can find its use in biosensing applications.