Performance Improvement of Refractometric Sensors Through Hybrid Plasmonic–Fano Resonances

Abstract

In this paper, we present a plasmonic refractometric sensor that works under normal incidence; allowing its integration on a fiber tip. The sensor's material and geometry exploit the large scattering cross-section given by high-contrast of the index of refraction subwavelength dielectric gratings. Our design generates a hybrid plasmonic-Fano resonance due to the interference between the surface plasmon resonance and the grating response. We optimize the sensor with a merit function that combines the quality parameter of the resonance and the field enhancement at the interaction volume where the plasmon propagates. Our device shows a high sensitivity (1000 nm/RIU) and a high Figure of Merit (775 RIU −1 ). Degradation in performance is negligible through a wide dynamic range up to 0.7 RIU. These quantitative parameters overperform compared to similar plasmonic sensors.

Plasmonic Sensors Based on Funneling Light Through Nanophotonic Structures

“…As it has been previously proved, the grating period can be changed to tune the resonance wavelengths at the desired spectral location: an increase in P produces a red-shift of the spectral response of the structure. The width of the aperture, or slot, is w = 50 nm and has been optimized to give the narrowest spectral response and the highest field confinement at the analyte interface (we consider water as the target analyte, n water = 1.33) [8]. This structure can be fabricated by successive depositions of metal and dielectric layers that are selectively etched after exposing the stack with the desired grating pattern through, for example, e-beam lithography.…”

Narrow Absorption in ITO-Free Perovskite Solar Cells for Sensing Applications Analyzed through Electromagnetic Simulation

“…Plasmonic resonances, excited at noble metal surfaces by nanostructures, result in deep spectral reflection dips. They generate large field enhancements near the metal surface [13]. This response is highly sensitive to changes in the optical characteristics of the surrounding materials.…”

Opto-Electronic Refractometric Sensor Based on Surface Plasmon Resonances and the Bolometric Effect

“…More precisely, they can also promote the excitation of surface plasmon resonances (SPR), hybrid Fano responses, guiding modes, and grating coupling. These phenomena generate a wide variety of spectral responses that improve the sensitivity, S B , and figure of merit (FOM) of the sensors [3][4][5]. The spectral line shape and the spatial and spectral location of the resonances depend on: (i) the dimensions of the nanostructure as well as, (ii) the optical properties of the chosen materials.…”

“…A plasmonic sensor incorporating nanophotonic structures provides tuneability for applications in biosensing, gas and liquids refractometers, and so forth [19][20][21]. It is also possible to considers normal incidence excitation through the substrate, while maintaining the sensor's performance competitive with some other previous strategies [3,4,12]. Furthermore, this could allow the integration of the sensor at the tip of an optical fiber.…”