Tunable and high-sensitivity sensing based on Fano resonance with coupled plasmonic cavities

Abstract

Tunable and high-sensitivity sensing based on Fano resonance is analytically and numerically investigated in coupled plasmonic cavities structure. To analyze and manipulate the Fano line shape, the coupled cavities are taken as a composite cavity that supports at least two resonance modes. A theoretical model is newly-established, and its results agree well with the finite difference time domain (FDTD) simulations for the plasmonic stub-pair structure. The detection sensitivity factor in coupled cavities approaches 6.541 × 107 m−1, which is an order of magnitude larger than single stub case. In addition, the wavelengths of resonant modes in the plasmonic stub-pair structure can be adjusted independently, which paves a new way for improving detection sensitivity. These discoveries hold potential applications for realizing tunable and highly integrated photonic devices.

Lifetime and nonlinearity of modulated surface plasmon for black phosphorus sensing application

“…We present a CMT analysis based on the cavity theory that describes the linear resonant modes of the cavity systems. 37,47 The linear absorption spectra for various Fermi energies, the electron scattering rate, side length of black phosphorus and the refractive indexes of superstrates with the FDTD method agree well with the theoretical description. Lifetime is important for the research of intrinsic loss for the m th mode and interaction between each mode and light field.…”

“…The incoming and outgoing waves are depicted by S ±,in(out) . The energy amplitude a 1 and a 2 of the BPSP resonators can be expressed as follows: 37,47 @ @t jai ¼ À iΩjai À Γ i jai À Γ w jai þ S þ;in jKi þ S À;in jKi À iMjai ð3Þ S þout ¼ ÀS Àin þ hKjai; ð4Þ…”

Plasmon drag effect with sharp polarity switching

“…According to equations (1) and (2), a change in the dielectric constant of the environment results in a shift of the SPP resonance angle. This effect is commonly used in plasmonic-based sensing applications [27][28][29][30][31]. As one can see in figure 4, adding a polystyrene layer (with a refractive index of 1.6 and thickness of ∼800 nm) on the top of the Ag/DVD structure, results in a shift of the switching point to higher angles, while the switching phenomenon occurs in both air and polymer environments.…”

“…Note that Fano resonances in plasmonic systems present a special interest for plasmonic-based sensing applications [31] as they are associated with sharp features in optical reflectivity and may significantly enhance the capability to resolve small changes in the dielectric constant of the environment and figure of merit of such sensors. However, optical monitoring of common plasmonic sensors requires a bulk optical setup, but electric reading can provide compact plasmonic devices for such applications.…”

High Sensitivity Plasmonic Metal-Dielectric-Metal Device With Two Side-Coupled Fano Cavities

“…The spectral lines of Fano resonance are much narrower as compared with the regular Lorentzian line shape. Thus, the plasmonic refractive index sensors based on various MDM waveguide coupled resonator systems with Fano resonance have been proposed and investigated [9][10][11][12][13][14]. Wen et al proposed an MDM-waveguide structure coupled with an end-coupled ring groove [9].…”