A Tunable Plasmonic Refractive Index Sensor with Nanoring-Strip Graphene Arrays

In the present study, we design a tunable plasmonic refractive index sensor with nanoring-strip graphene arrays. The calculations prove that the nanoring-strip have two transmission dips. By changing the strip length L of the present structure, we find that the nanoring-strip graphene arrays have a wide range of resonances (resonance wavelength increases from 17.73 μm to 28.15 μm). When changing the sensing medium refractive index nmed, the sensitivity of mode A and B can reach 2.97 μm/RIU and 5.20 μm/RIU. By changing the doping level ng, we notice that the transmission characteristics can be tuned flexibly. Finally, the proposed sensor also shows good angle tolerance for both transverse magnetic (TM) and transverse electric (TE) polarizations. The proposed nanoring-strip graphene arrays along with the numerical results could open a new avenue to realize various tunable plasmon devices and have a great application prospect in biosensing, detection, and imaging.

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

Nanomaterials ◽

10.3390/nano11082097 ◽

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 ◽

...

Keyword(s):

Refractive Index ◽

Plasmon Resonance ◽

Fano Resonance ◽

High Sensitivity ◽

Metal Nanostructures ◽

Refractive Index Sensor ◽

Metal Insulator ◽

Wide Range ◽

Metal Insulator Metal ◽

Mode 2

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).

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Enhanced Plasmonic Resonance Characteristics of AgNRs–Gold Film Hybrid System

Frontiers in Chemistry ◽

10.3389/fchem.2020.553541 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yanping Yin ◽

Jin Zhu ◽

Zaoji Wang ◽

Guojun Ma ◽

Huining Yuan ◽

...

Keyword(s):

Refractive Index ◽

Aspect Ratio ◽

Gold Film ◽

Spectral Response ◽

Surrounding Medium ◽

Resonance Wavelength ◽

Spectral Shift ◽

Refractive Index Sensor ◽

Gap Size ◽

Refractive Index Sensitivity

In recent years, the plasma gap resonance maintained by metal-film-coupled nanostructures has attracted extensive attention. This mainly originates from its flexible control of the spectral response and significantly enhanced field strength at the nanoparticle–film junction. In the present study, the tunability of local surface plasmon resonances (LSPRs) of nanorods coupled to a gold film is studied theoretically. To this end, the plasmonic resonances in the nanostructure of individual silver nanorod–gold film (AgNR-film) with different parameters are investigated. Obtained results show that the refractive index sensitivity (S) of nanostructures to the environment increases as the aspect ratio (Ar) of nanostructures increase. It is found that when the aspect ratio (Ar) is set to 3.5, the figure of merit (FOM) is the highest. Moreover, the variation in the gap distances of the nanorod monomer–gold film, electric field distribution of nanorods dimer, and the corresponding impact on the gold film are studied. It is concluded that the gap size of nanostructures has an exponential correlation with the resonance wavelength. Considering the remarkable influence of the gap size and the surrounding medium environment on the spectral shift of AgNR-film nanostructures, potential applications of the structure as a refractive index sensor and biomolecule measurement are proposed.

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A theoretical study of optically enhanced transmission characteristics of subwavelength metal Y-shaped arrays and its application on refractive index sensor

Results in Physics ◽

10.1016/j.rinp.2019.102495 ◽

2019 ◽

Vol 15 ◽

pp. 102495 ◽

Cited By ~ 11

Author(s):

Yunping Qi ◽

Yue Wang ◽

Xuewei Zhang ◽

Chuqin Liu ◽

Bingbing Hu ◽

...

Keyword(s):

Refractive Index ◽

Theoretical Study ◽

Refractive Index Sensor ◽

Transmission Characteristics ◽

Enhanced Transmission

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Sensitivity Enhancement of a Concave Shaped Optical Fiber Refractive Index Sensor Covered with Multiple Au Nanowires

Sensors ◽

10.3390/s19194210 ◽

2019 ◽

Vol 19 (19) ◽

pp. 4210 ◽

Cited By ~ 9

Author(s):

Pathak ◽

Rahman ◽

Singh ◽

Kumari

Keyword(s):

Refractive Index ◽

Structural Parameters ◽

Localized Surface Plasmon ◽

Refractive Index Sensor ◽

Au Film ◽

The Core ◽

Enhanced Sensitivity ◽

Guided Mode ◽

Wide Range ◽

Au Nanowires

In the present paper, a new kind of concave shaped refractive index sensor (CSRIS) exploiting localized surface plasmon resonance (LSPR) is proposed and numerically optimized. The LSPR effect between polaritons and the core guided mode of designed CSRIS is used to enhance the sensing performance. The sensor is characterized for two types of sensing structures coated with gold (Au) film and Au nanowires (AuNWs), respectively. The influence of structural parameters such as the distance (D) of the concave shaped channel (CSC) from the core, the diameter of the nanowire (dn) and the size (s) of the CSC are investigated here. In comparison to Au film, the AuNWs are shown to significantly enhance the sensitivity and the performance of the designed sensor. An enhanced sensitivity of 4471 nm/RIU (refractive index unit) is obtained with AuNWs, for a wide range of analytes refractive index (na) varying between 1.33 to 1.38. However, for conventional Au film; the sensitivity of 808.57 nm/RIU is obtained for the same range of analytes.

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Highly Sensitive Plasmonic Refractive Index Sensor Based on Dual D-Shaped Photonic Crystal Fiber with Aluminum Nitride-Silver Films

10.21203/rs.3.rs-1077705/v1 ◽

2021 ◽

Author(s):

Sanfeng Gu ◽

Wei Sun ◽

Meng Li ◽

Ming Deng

Keyword(s):

Refractive Index ◽

Photonic Crystal ◽

Aluminum Nitride ◽

Photonic Crystal Fiber ◽

Low Cost ◽

Optical Loss ◽

High Sensitivity ◽

Resonance Wavelength ◽

Refractive Index Sensor ◽

Crystal Fiber

Abstract A dual-core and dual D-shaped photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensor with silver and Aluminum Nitride (AlN) films is designed. The distribution characteristics of the electromagnetic fields of core and plasmon modes, as well as the sensing properties are numerically studied by finite element method (FEM). The structure parameters of the designed sensor are optimized by the optical loss spectrum. The results show the resonance wavelength variation of 489 nm for the refractive index (RI) range of 1.36~1.42. In addition, a maximum wavelength sensitivity of 13400 nm/RIU with the corresponding RI resolution of 7.46×10-6 RIU is obtained in the RI range of 1.41~1.42. The proposed sensor with the merits of high sensitivity, low cost and simple structure has a wide application in the fields of RI sensing, such as hazardous gas detection, environmental monitoring and biochemical analysis.

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Wide Range Refractive Index Sensor Using a Birefringent Optical Fiber

10.21203/rs.3.rs-172462/v1 ◽

2021 ◽

Author(s):

Moutusi De ◽

Vinod Kumar Singh

Keyword(s):

Refractive Index ◽

Near Infrared ◽

High Sensitivity ◽

Infrared Region ◽

Device Fabrication ◽

Refractive Index Sensor ◽

Potential Candidate ◽

Wide Range ◽

Analyte Detection ◽

Birefringent Optical Fiber

Abstract In this article, an efficient high birefringent D-shaped photonic crystal fiber (HB-D-PCF) plasmonic refractive index sensor is reported. It is able to work over a long low refractive index (RI) analyte range from 1.29 to 1.36. This modified simple structured hexagonal PCF has high birefringence in the near-infrared region. A thin gold film protected by a titanium dioxide (TiO2) layer is deposited on the D-surface of the PCF which acts as surface plasmon active layer. The sensor consists of an analyte channel on the top of the fiber. The performance of the HB-D-PCF is analyzed based on finite element method (FEM). Both wavelength and amplitude interrogation techniques are applied to study the sensing performance of the optimized sensor. Numerical results show wavelength and amplitude sensitivity of 9245nm/RIU and 1312 RIU-1 respectively with high resolution. Owing to the high sensitivity, long range sensing ability as well as spectral stability the designed HB-D-PCF SPR sensor is a potential candidate for water pollution control, glucose concentration testing, biochemical analyte detection as well as portable device fabrication.

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Bidirectional Angle-Tolerant Polarization-Tuned Filtering and Wide-Range Refractive Index Sensing Based on Metal Film Coated Nanograting

Nanomaterials ◽

10.3390/nano11010047 ◽

2020 ◽

Vol 11 (1) ◽

pp. 47

Author(s):

Wenli Cui ◽

Qiannan Wu ◽

Bo Chen ◽

Xufeng Li ◽

Xiaolin Luo ◽

...

Keyword(s):

Refractive Index ◽

Metal Film ◽

High Performance ◽

Incident Angle ◽

Single Layer ◽

Transverse Magnetic ◽

Photonic Devices ◽

Biomedical Sensors ◽

Dual Channel ◽

Wide Range

The miniaturization and integration of photonic devices are new requirements in the fast-growing optics field. In this paper, we focus on a feature-rich sub-wavelength nanograting-coated single-layer metal film. The numerical results show that the reflection behaviors of this proposed structure can realize bidirectional dual-channel ultra-narrowband polarized filtering and bidirectional wavelength-modulated sensing in a wide refractive index (RI) range from 1.0 to 1.4 for incident angle of 10° with transverse-magnetic (TM) polarized illumination at wavelengths between 550 nm to 1500 nm. Moreover, the bidirectional properties of filtering and sensing are not obviously decreased when increasing incident angle from 10° to 30°, and decreasing incident angle from 10° to 0°. The calculated RI sensitivity can be up to 592 nm/RIU with a high figure of merit (FOM) of 179.4 RIU−1. More to the point, this nanograting has a simple structure and is less sensitive to the height and shape of grating ridge, which provides great convenience for the fabrication of devices. The other thing that is going on is that this structure can also realize synchronously tunable color filtering, including green to red, with high color purity in the visible band by choosing the period. The underlying physical mechanism is analyzed in detail, and is primarily attributed to surface plasmon polariton (SPP) resonance and dipole resonance at double plasmon resonance wavelengths. This work has tremendous potential in developing multipurpose and high-performance integrated optical devices such as spectral filters, colored displays and plasmon biomedical sensors.

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Design of graded honeycomb radar absorbing structure with wide-band and wide-angle properties

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078718001460 ◽

2018 ◽

Vol 11 (2) ◽

pp. 143-150 ◽

Cited By ~ 2

Author(s):

Yuchen Zhao ◽

Fang Ren ◽

Li He ◽

Jinsheng Zhang ◽

Yanning Yuan ◽

...

Keyword(s):

Transverse Electric ◽

Incident Angle ◽

Wide Band ◽

Transverse Magnetic ◽

Magnetic Polarization ◽

Wide Range ◽

Transverse Magnetic Polarization ◽

Radar Absorbing Structure ◽

Theoretical Limitation ◽

Good Agreement

AbstractIn this paper, the design of a graded honeycomb radar absorbing structure (RAS) is presented to realize both a wide bandwidth and absorption over a wide range of angles. For both transverse-electric and transverse-magnetic polarization, a fractional bandwidth of more than 118.6% is achieved for at least a 10 dB reflectivity reduction when the incident angle is <45°, an 8 dB reduction when the incident angle is <55° and a 5 dB reduction when the incident angle is <70°. Meanwhile the 10 dB reduction upper angle limit is approximately 30° for the uniform coating honeycomb RAS in the literature, which loses its absorbing ability when the incident angle is larger than 55°. Furthermore, the total thickness of our design is 10.7 mm, which is only approximately 1.29 times that of the theoretical limitation. The good agreement between the calculated, simulated, and measured results demonstrates the validity of this optimization.

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