Study on the Nanosensor Based on a MIM Waveguide with a Stub Coupled with a Horizontal B-Type Cavity

Abstract

Due to their compact size and high sensitivity, plasmonic sensors have become a hot topic in the sensing field. A nanosensor structure, comprising the metal–insulator–metal (MIM) waveguide with a stub and a horizontal B-Type cavity, is designed as a refractive index sensor. The spectral characteristics of proposed structure are analyzed via the finite element method (FEM). The results show that there is a sharp Fano resonance profile, which is excited by a coupling between the MIM waveguide and the horizontal B-Type cavity. The normalized HZ field is affected by the difference value between the outer radii R1 and R2 of the semi-circle of the horizontal B-Type cavity greatly. The influence of every element of the whole system on sensing properties is discussed in depth. The sensitivity of the proposed structure can obtain 1548 nm/RIU (refractive index unit) with a figure of merit of 59. The proposed structure has potential in nanophotonic sensing applications.

Improved Refractive Index-Sensing Performance of Multimode Fano-Resonance-Based Metal-Insulator-Metal Nanostructures

“…If varying the original resonator can change the equivalent optical path of the Fabry-Perot cavity and influence the SPPs modes in the original resonator, which will excite new optical properties in the plasmonic sensor. Recently, several MIM waveguides with different patterns of resonators have been studied, such as circular/rectangular ring [47], bowtie shaped cavity [50], tooth-shaped cavity [51], X-shaped [52], U-shaped [53], B-shaped [54], T-type [55], M-type [56] and key-shaped [36] resonators, elliptical-shaped trapezoid cavity [57], all-grating racetrack cavity [58], stub coupled with a square cavity [54], metallic nanorods in hexagonal configuration [25], and so forth.…”

Plasmonic Narrowband Filter Based on an Equilateral Triangular Resonator with a Silver Bar

“…Consequently, more and more researchers are paying attention to its applications in the modulator, optical switches, wavelength division multiplexing (WDM), Mach-Zehnder, and splitters [19][20][21]. It is worth noting that recent studies have aimed to design different structures for higher FOM and S [22][23][24][25], and through changing the external size of resonators to make the whole structure tunable [26,27]. Additionally, a lot of structures are designed to obtain higher quality factor (Q).…”