Plasmonic refractive index sensor with multi-channel Fano resonances based on MIM waveguides

2020 ◽  
Vol 34 (16) ◽  
pp. 2050173
Author(s):  
Yihong Fang ◽  
Kunhua Wen ◽  
Zhengfeng Li ◽  
Bingye Wu ◽  
Zicong Guo

A multi-channel Fano resonant structure is proposed and analyzed based on subwavelength metal–insulator–metal (MIM) waveguides. First, two MIM output ports associated with specific side-coupled cavities are designed to locate at the center and quarter positions of an end-coupled cavity, respectively. Since the interference between the dark and bright modes, dual-channel Fano resonances with asymmetrical lines shapes are obtained at both ports, respectively. High sensitivity and figure of merits are investigated. Besides, phase shifts are also investigated leading to positive and negative group delays available at the Fano peaks and dips, respectively. Likewise, two extra output ports with identical resonant cavities are placed on the other side of the end-coupled cavity. In this case, four-channel Fano resonances with considerable performances are obtained. The proposed structure is analyzed by the coupled mode theory and the finite difference time domain method. It is believed this device can be used as a chip-scale refractive index sensor and optical filter.

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3181 ◽  
Author(s):  
Kunhua Wen ◽  
Li Chen ◽  
Jinyun Zhou ◽  
Liang Lei ◽  
Yihong Fang

In this paper, multiple Fano resonances preferred in the refractive index sensing area are achieved based on sub-wavelength metal-insulator-metal (MIM) waveguides. Two slot cavities, which are placed between or above the MIM waveguides, can support the bright modes or the dark modes, respectively. Owing to the mode interferences, dual Fano resonances with obvious asymmetrical spectral responses are achieved. High sensitivity and high figure of merit are investigated by using the finite-difference time-domain (FDTD) method. In view of the development of chip-scale integrated photonics, two extra slot cavities are successively added to the structure, and consequently, three and four ultra-sharp Fano peaks with considerable performances are obtained, respectively. It is believed that this proposed structure can find important applications in the on-chip optical sensing and optical communication areas.


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2097
Author(s):  
Yuan-Fong Chou Chau ◽  
Chung-Ting Chou Chao ◽  
Siti Zubaidah Binti Haji Jumat ◽  
Muhammad Raziq Rahimi Kooh ◽  
Roshan Thotagamuge ◽  
...  

This work proposed a multiple mode Fano resonance-based refractive index sensor with high sensitivity that is a rarely investigated structure. The designed device consists of a metal–insulator–metal (MIM) waveguide with two rectangular stubs side-coupled with an elliptical resonator embedded with an air path in the resonator and several metal defects set in the bus waveguide. We systematically studied three types of sensor structures employing the finite element method. Results show that the surface plasmon mode’s splitting is affected by the geometry of the sensor. We found that the transmittance dips and peaks can dramatically change by adding the dual air stubs, and the light–matter interaction can effectively enhance by embedding an air path in the resonator and the metal defects in the bus waveguide. The double air stubs and an air path contribute to the cavity plasmon resonance, and the metal defects facilitate the gap plasmon resonance in the proposed plasmonic sensor, resulting in remarkable characteristics compared with those of plasmonic sensors. The high sensitivity of 2600 nm/RIU and 1200 nm/RIU can simultaneously achieve in mode 1 and mode 2 of the proposed type 3 structure, which considerably raises the sensitivity by 216.67% for mode 1 and 133.33% for mode 2 compared to its regular counterpart, i.e., type 2 structure. The designed sensing structure can detect the material’s refractive index in a wide range of gas, liquids, and biomaterials (e.g., hemoglobin concentration).


Sensors ◽  
2017 ◽  
Vol 17 (4) ◽  
pp. 784 ◽  
Author(s):  
Yue Tang ◽  
Zhidong Zhang ◽  
Ruibing Wang ◽  
Zhenyin Hai ◽  
Chenyang Xue ◽  
...  

2015 ◽  
Vol 742 ◽  
pp. 46-49 ◽  
Author(s):  
Ting Ting Tang ◽  
Li Luo

We propose a refractive sensor based on directional coupling between two metal-insulator-metal (MIM) waveguides to measure the refractive index change of the insulator, which is designed to be with a structure of metal-insulator-metal-insulator-metal (MIMIM) in which surface plasmon waves (SPW) are excited. The propagation properties are analyzed by coupled mode theory, and the expressions about the coupling coefficient, coupling length and sensitivity are derived. The sensing properties based on simulation results are also discussed. Compared with a dielectric waveguide, the total size of our sensor with MIMIM waveguide is about one tenth that with dielectric materials, while the sensitivity is improved ten times larger than the former.


2022 ◽  
Author(s):  
Vahid Najjari ◽  
Saeed Mirzanejhad ◽  
Amin Ghadi

Abstract A plasmonic refractive index sensor including a Metal-Insulator-Metal waveguide (MIM) with four teeth is proposed. Transmittance (T), Sensitivity (S) and Figure of Merit (FOM) investigated numerically and analysed via Finite Difference Time Domain method (FDTD). The simulation results show the generation of double Fano resonances in the system that the resonance wavelength and the resonance line-shapes can be adjusted by changing the geometry of the device. By optimizing the structure in the initial configuration, the maximum sensitivity of 1078nm/RIU and FOM of 3.62×105 is achieved. Then change the structure parameters. In this case, the maximum sensitivity and FOM are 1041nm/RIU and 2.94×104 respectively, thus two detection points can be used for the refractive index sensor. Due to proper performance and adjustable Fano resonance points, this structure is significant for fabricating sensitive refractive index sensor and plasmonic bandpass filter.


2022 ◽  
Author(s):  
Haowen Chen ◽  
Yunping Qi ◽  
Jinghui Ding ◽  
Yujiao Yuan ◽  
Zhenting Tian ◽  
...  

Abstract A plasmonic resonator system consisting of a metal-insulator-metal waveguide and a Q-shaped resonant cavity is proposed in this paper. The transmission properties of surface plasmon polaritons in this structure are investigated using the finite difference in time domain (FDTD) method, and the simulation results contain two resonant dips. And the physical mechanism is studied by the multimode interference coupled mode theory (MICMT), the theoretical results are in highly consistent with the simulation results. Furthermore, the parameters of the Q-shaped cavity can be controlled to adjust two dips respectively. The refractive index sensor with a sensitivity of 1578nm/RIU and figure of merit (FOM) of 175, performs better than most of the similar structures. Therefore, the results of the study are instructive for the design and application of high sensitivity nanoscale refractive index sensors.


Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 125
Author(s):  
Shubin Yan ◽  
Haoran Shi ◽  
Xiaoyu Yang ◽  
Jing Guo ◽  
Wenchang Wu ◽  
...  

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.


2021 ◽  
Vol 2125 (1) ◽  
pp. 012005
Author(s):  
Yang Zhang

Abstract A tunable dual Fano-like plasmonic structure consisting of metal-insulator-metal (MIM), baffle and a rectangular cavity containing two identical rectangular metal blocks is obtained. Numerical simulation results show that there are dual Fano resonances in the transmission spectrum of the structure, which can be tuned by changing the geometric parameters of the structure. In addition, due to the apparent asymmetry of the Fano resonances, the system was developed as an effective refractive index sensor (RIS) with a sensitivity of 853 nm/RIU and figure of merit (FOM) of 1631. It is considered that this structure has important application value in high integrated photonic circuit.


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