Highly Sensitive and Tunable Plasmonic Sensor Based on a Nanoring Resonator with Silver Nanorods

Abstract

We numerically and theoretically investigate a highly sensitive and tunable plasmonic refractive index sensor that is composed of a metal-insulator-metal waveguide with a side-coupled nanoring, containing silver nanorods using the finite element method. Results reveal that the presence of silver nanorods in the nanoring has a significant impact on sensitivity and tunability performance. It gives a flexible way to tune the system response in the proposed structure. Our designed sensor has a sensitivity of 2080 nm/RIU (RIU is the refractive index unit) along with a figure of merit and a quality factor of 29.92 and 29.67, respectively. The adequate refractive index sensitivity can increase by adding the silver nanorods in a nanoring, which can induce new surface plasmon polaritons (SPPs) modes that cannot be found by a regular nanoring. For a practical application, a valid introduction of silver nanorods in the nanoring can dramatically reduce the dimension of the proposed structure without sacrificing performance.

Ultrawide Bandgap and High Sensitivity of a Plasmonic Metal-Insulator-Metal Waveguide Filter with Cavity and Baffles

“…Figure 5 a,b shows the proposed structure’s transmittance spectra without/with Ag baffles concerning L = 300 nm and L = 600 nm. To test the device’s sensitivity performance, we chose the refractive index values in the range of 1.01–1.09, and the other range of refractive index values has the same trend of transmittance spectrum based on our simulations [ 20 ]. The refractive index ( n ) is varied from 1.01, 1.05 to 1.09 at the interval of 0.04, respectively, while the other structural parameters w, g , and d are 50, 10, and 30 nm, respectively.…”

“…Fortunately, only four structural parameters (i.e., w, g , d , and L ) are considered in our design. In the previous simulations, we fixed w = 50 nm for the fundamental mode to excite the straight waveguide and g = 10 nm for efficient coupling between the straight waveguide and the cavity [ 20 , 32 ]. Next, the four structural parameters, d, L , w, and g, will be inspected in detail.…”

“…Waveguides compose of an insulator placed between two metals term as metal-insulator-metal (MIM) waveguides possessing transmitting SPPs modes that are strongly restricted in a dielectric region with an adequate propagation length of SPPs [ 17 , 18 , 19 ]. A traditional plasmonic MIM waveguide consists of the straight waveguides and the resonance cavities [ 20 , 21 ]. Taking advantage of MIM waveguides, various plasmonic devices can be designed and manufactured [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

“…Various resonance cavities in plasmonic MIM waveguide using single or multiple cavities have theoretically analyzed and numerically investigated [ 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. Many efforts have focused on enlarging the cavity size to achieve high sensitivity as the effective cavity length has a linear relationship to the increased resonance wavelength [ 20 , 37 , 53 ]. Although the higher sensitivity can be obtained, the drawback of enlarging device size and manufacturing complexity are presented.…”

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

“…Butt et al proposed a nanosensor based on a metal-insulator-metal waveguide with the sensitivity of 1948.67 nm/RIU [34]. Chao et al proposed an MIM waveguide with a side-coupled ring with several silver rods with the high sensitivity of 2080 nm/RIU [35]. At present, the number of high sensitivity devices, whose sensitivities are more than 10,000 nm/RIU [36], is small.…”