Nano-plasmonic refractive index sensor based on metallic slit loaded stub resonator

Abstract

The combination of optical sensing phenomenon with Nano science is a new paradigm shift in point of care sensing devices. Here, a nano-sensor based on propagating Plasmons is investigated. Due to unique feature of plasmonics having long transmission range and confined the signal beyond diffraction limit, the sensor is designed with metal–insulator-metal (MIM) geometry of plasmonic waveguide. The stub resonator is coupled to MIM waveguide for the desired filter characteristics. The metallic slit is incorporated in the resonating structure and the metallic slit is off-center in resonating structure. The presence of the slit tunes the condition of resonance and Fano interference phenomenon emerges. The device is calibrated according to change in the value of refractive index of analyte and we can observe linear relation between the refractive index of analyte and resonance wavelength. The maximum value of sensitivity is achieved as 1990 nm/ RIU. The proposed geometry may open a new path for nano-sensing based optical chips.