Formation Laws of Direction of Fano Line-Shape in a Ring MIM Plasmonic Waveguide Side-Coupled with a Rectangular Resonator and Nano-Sensing Analysis of Multiple Fano Resonances

Abstract

Plasmonic MIM (metal-insulator-metal) waveguides based on Fano resonance have been widely researched. However, the regulation of the direction of the line shape of Fano resonance is rarely mentioned. In order to study the regulation of the direction of the Fano line-shape, a Fano resonant plasmonic system, which consists of a MIM waveguide coupled with a ring resonator and a rectangle resonator, is proposed and investigated numerically via FEM (finite element method). We find the influencing factors and formation laws of the ‘direction’ of the Fano line-shape, and the optimal condition for the generation of multiple Fano resonances; and the application in refractive index sensing is also well studied. The conclusions can provide a clear theoretical reference for the regulation of the direction of the line shape of Fano resonance and the generation of multi Fano resonances in the designs of plasmonic nanodevices.

A Review of Photonic Sensors Based on Ring Resonator Structures: Three Widely Used Platforms and Implications of Sensing Applications

“… Schematic of some of the few recently proposed plasmonic RR-based sensors with unique cavity shapes, ( a ) ring resonator [ 136 ], ( b ) square ring cavity filled with a functional polymer [ 29 ], ( c ) ring MIM WG side coupled with a rectangular resonator [ 138 ], ( d ) rectangular resonator and a ring resonator [ 139 ], ( e ) notched ring resonator [ 140 ], ( f ) rectangular hollow cavity with metallic island [ 137 ], ( g ) concentric double MIM rings [ 141 ], ( h ) square ring-shaped resonator containing silver nanorods [ 142 ], ( i ) connected concentric double ring resonator [ 143 ]. …”

Metal‐insulator‐metal waveguide‐based plasmonic sensors: Fantasy or truth—A critical review

“…Metal‐insulator‐metal (MIM) waveguide (WG)‐based plasmonic sensor designs based on different cavity shapes, (a) side coupled square cavity [42], (b) end coupled ring cavity [39], (c) asymmetric structure [43], (d) ring and a rectangular [44], (e) side coupled ring and a defect [45], (f) end coupled square cavity [46], (g) side coupled split ring cavity [30], (h) cavity with defect [47], (i) T‐shaped cavity with nanorods [48], (j) l ‐shaped cavity [49], (k)dual hexagonal cavities [19], (l) side coupled ring with baffles [50], (m) horizontal eight shape [51], (n) horn shaped cavity [52], (o) racetrack and circular cavity [53]. …”

“…F I G U R E 2 Metal-insulator-metal (MIM) waveguide (WG)-based plasmonic sensor designs based on different cavity shapes, (a) side coupled square cavity [42], (b) end coupled ring cavity [39], (c) asymmetric structure [43], (d) ring and a rectangular [44], (e) side coupled ring and a defect [45], (f) end coupled square cavity [46], (g) side coupled split ring cavity [30], (h) cavity with defect [47], (i) T-shaped cavity with nanorods [48], (j)…”

A single-mode tunable plasmonic sensor based on an 8-shaped resonator for cancer cell detection

“…Since the properties of plasmonic MIM waveguides and filters are highly dependent upon the refractive index of the insulator material, they can be utilized to measure refractive index changes of the environment 27 . Thus, plasmonic MIM structures provides significant advantages for subwavelength refractive index sensing 28 .…”