Three layers of periodic artificial metamaterial sensing structure (including the upper metal particles, intermediate dielectric layer, and the lower reflective layer) with ultra-narrow band absorption were designed. The resonance characteristics and sensing properties were analyzed by the finite difference time domain (FDTD) method. The effect of localized surface plasmon resonance (LSPR) was obviously observed at the resonance wavelength of 911 nm, and it achieves nearly perfect absorption of exceeding 98% with a full width at half maximum (FWHM) of 3.5 nm. In addition, a wavelength sensitivity of 542 nm/RIU with a figure of merit (FOM) of 155 was obtained in the refractive index (RI) range from 1.00 to 1.35, which has a wide range of applications. The results show that the proposed structure has high absorption and RI sensitivity, which is suitable for bioengineering and medical detection.
相似文献We theoretically propose a surface plasmon resonance (SPR)-based fiber optic refractive index (RI) sensor. A surface plasmon exciting metallic grating formed with the alternation of indium tin oxide (ITO) and silver (Ag) stripes is considered on the core of the fiber. A thin film of silicon is used as an overlay. Silicon film not only protects the metallic grating from oxidation but also enhances the field to improve the device sensitivity. The sensor is characterized in terms of sensitivity, detection accuracy (DA), figure of merit (FoM), and quality factor (QF). The maximum sensitivity in the RI range 1.33 to 1.38 refractive index unit (RIU) is reported to be?~25 µm/RIU in infra-red region of investigation.
相似文献In this report, a novel D-shaped long-range surface plasmon resonance (LRSPR) fiber base sensor has been introduced. The demonstration of proposed sensor involves two D-shaped silver-coated models to study the sensitivity responses. The entire study with the constructed models is based on a single-mode fiber. The models are multilayered consisting of metal, dielectric, and analyte as separate layers. Silver (Ag) and magnesium fluoride (MgF2) strips are used as metal and dielectric layers respectively. The constituency of analyte as an interface excellently standardized the models for sensitivity detection. In this report, a large range of analyte refractive indices (RI) which varies from 1.33 to 1.38 is appraised for the proposed models to characterize the sensitivity. The entire context is encompassed by the wavelength region from 450 to 850 nm with an interval of 20 nm. Sensitivities in this report are measured based on the analyte position from the core and metal for both models. For each of the two models, the analyte is placed as the top layer. RIs of the applied metal (Ag) are measured using the Drude-Lorentz formula. The simulated sensitivities for model-1 and model-2 vary from 6.3?×?103 nm/RIU to 8.7?×?103 nm/RIU.
相似文献A highly sensitive dual-core photonic crystal fiber based on a surface plasmon resonance (PCF-SPR) biosensor with a silver-graphene layer is described. The silver layer with a graphene coating not only prevents oxidation of the silver layer but also can improve the silver sensing performance due to the large surface-to-volume ratio of graphene. The dual-core PCF-SPR biosensor is numerically analyzed by the finite-element method (FEM). An average spectral sensitivity of 4350 nm/refractive index unit (RIU) in the sensing range between 1.39 and 1.42 and maximum spectral sensitivity of 10,000 nm/RIU in the sensing range between 1.43 and 1.46 are obtained, corresponding to a high resolution of 1 × 10−6 RIU as a biosensor. Our analysis shows that the optical spectra of the PCF-SPR biosensor can be optimized by varying the structural parameters of the structure, suggesting promising applications in biological and biochemical detection.
相似文献In this paper, individual split Au square nanorings were numerically proposed as novel substrates for surface-enhanced Raman and hyper-Raman scattering (SERS and SEHRS) simultaneously. The peak wavelengths of their localized surface plasmon resonance (LSPR) fall in the near-infrared and visible light regions, respectively, which are able to be finely tuned to match well with the wavelengths of the incident laser and hyper-Raman scattered light beams. Their SEHRS and SERS performances along with electromagnetic (EM) field distributions are numerically investigated by finite element method. With the enhancement of near electric-fields generated by LSPRs, the maximum SEHRS and SERS enhancement factors are demonstrated to reach 1.22?×?1012 and 108, respectively. Meanwhile, the corresponding SERS-based refractive index (RI) sensitivity factor reaches as high as 258 nm/RIU and 893 nm/RIU, at visible and near-infrared wavelengths, respectively. The proposed structure holds great promise both for developing SEHRS- and SERS-based RI sensing substrates, which shows strong potential applications in nanosensing and enhanced Raman scattering.
相似文献Due to the advantage of improving the sensing performance, narrow-band metamaterial perfect absorbers (MPAs) have attracted much attention in the sensor field. Here, we propose an ultra-narrow-band infrared absorber (UNBIRA) based on localized surface plasmon resonance. The peak absorption of the UNBIRA exceeds 99% with the full width at half maximum (FWHM) of 1.94 nm and 6.32 nm for transverse electric (TE) wave and transverse magnetic (TM) wave in 1.5–1.8 μm. The corresponding Q-factors for TE wave and TM wave are 817 and 266, respectively. When used as an infrared refractive index sensor, the sensitivity of UNBIRA is as high as 1632.5 nm/RIU for TE wave and 1647.5 nm/RIU for TM wave. Accordingly, the figure of merits (FOMs) of 816.2/RIU for TE wave and 260.7/RIU for TM wave are achieved. This UNBIRA possesses a simple geometry structure and an excellent sensing performance, implying a great potential for application of ultra-narrow infrared sensing or detecting.
相似文献Dividing a metal nanoparticle into smaller components and the occurrence of the plasmonic phenomenon in the gap between these components can improve the sensitivity of the detector to variation of the refraction coefficient of liquid. In this paper, in a constant volume of metal, a golden disk is divided into two rings and one smaller disk. With a proper arrangement of these components, the surface plasmon resonance phenomenon takes place at the wavelength of 945.7 nm. The occurrence of this phenomenon increases the field in the distance between nanoparticles surrounded by liquid. The sensitivity of the detector that designed using nanodisks is 300 nm/RIU while it increases to 500 nm/RIU for the new structure. The increase of LSPR displacement, for a variation of 0.01 in the liquid refraction coefficient, from 3 nm for a disk to 5 nm for a proposed structure verifies a 67% improvement in the sensitivity of the sensor.
相似文献In this article, a surface plasmon resonance (SPR) biosensor based on D-typed optical fiber coated by Al2O3/Ag/Al2O3 film is investigated numerically. Resonance in near infrared with an optimized architecture is achieved. Refractive index sensitivity of 6558 nm/RIU (refractive index unit) and detection limit of 1.5 × 10−6 RIU, corresponding to 0.4357 nm/μM and detection limit of 23 nM in BSA (bovine serum albumin) concentration sensing, are obtained. The analysis of the performance of the sensor in gaseous sensing indicates that this proposed SPR sensor is much suitable for label-free biosensing in aqueous media.
相似文献In this study, we demonstrate the design of a photonic crystal fiber (PCF)-based plasmonic sensor to measure the glucose level of urine. The sensor is designed by placing a small segment of PCF between a lead-in and a lead-out single-mode fiber. We utilize the finite element method to simulate the proposed plasmonic sensor for the measurement of glucose level in urine. To offer external sensing, the cladding layer of the PCF was coated by a thin layer of gold where the gold-coated PCF was immersed in the urine sample. As a result, the urine can easily interact with the plasmonic layer of the sensor. In the outermost laser of the PCF, we considered a perfectly matched layer as a boundary condition. The simulation results confirm excellent wavelength and amplitude sensitivities where the maximum wavelength sensitivity was 2500 nm/RIU and amplitude sensitivity was 152 RIU?1 with a sensing resolution of 4?×?10?6. For optimization of the plasmonic sensor, we varied the physical parameters of the cladding air holes and the thickness of the gold layer during the simulation. We strongly believe that the proposed plasmonic sensor will play a significant role to pave the way for achieving a simple but effective PCF-based glucose sensor.
相似文献A surface plasmon resonance (SPR) sensor based on a photonic crystal fiber (PCF) is proposed for low refractive index (RI) detection. The core of PCF is formed by two-layer air walls and either layer is composed of six identical sector rings with negative curvature. Plasmonic material gold (Au) is coated on the external cladding surface. Finite element method (FEM) is applied to investigate the performance of the SPR sensor. Results show that the sensor is independent of polarization due to the coincident coupling properties of the two polarized modes. Additionally, in low RI ranging from 1.20 to 1.33, the sensor keeps a high spectral sensitivity with an average value of 7738 nm/RIU. When RI varies from 1.32 to 1.33, the resolution reaches to its maximum of 8.3 × 10−6. The proposed sensor shows much significance in low RI detection, which is promising in real-time measurement for medical, water pollution, and humidity.
相似文献In the present work, a novel surface plasmon resonance (SPR) sensor consisting of the nickel (Ni) film with hybrid structure of blue phosphorene (BlueP)/transition metal dichalcogenides (TMDCs) is reported. By optimizing the thickness of Ni layer and BlueP/TMDCs, the maximum sensitivity with 270°/RIU for the Ni-BlueP/WS2 is achieved. Use of BlueP/TMDCs layer facilitates the sensitivity due to its high electron concentration, high mobility, optical, and electronic properties. Compared with the conventional Ni-based SPR sensor, the sensitivity of the proposed one is enhanced up to ~ 60.7%. We hope that the SPR sensor has potential application prospects in chemical detection, medical diagnostic, optical sensing, etc. due to its high sensitivity.
相似文献A self-referencing plasmonic platform is proposed and analyzed. By introducing a thin gold layer below a periodic two-dimensional nano-grating, the structure supports multiple modes including localized surface plasmon resonance (LSPR), surface plasmon resonance (SPR), and Fabry-Perot resonances. These modes get coupled to each other creating multiple Fano resonances. A coupled mode between the LSPR and SPR responses is spatially separated from the sensor surface and is not sensitive to refractive index changes in the surrounding materials or surface attachments. This mode can be used for self-referencing the measurements. In contrast, the LSPR dominant mode shifts in wavelength when the refractive index of the surrounding medium is changed. The proposed structure is easy to fabricate using conventional lithography and electron beam deposition methods. A bulk sensitivity of 429 nm/RIU is achieved. The sensor also has the ability to detect nanometer thick surface attachments on the top of the grating.
相似文献Highly sensitive surface plasmon resonance (SPR) sensor consisting of Ag-Pt bimetallic films sandwiched with 2D materials black phosphorus (BP) and graphene over Pt layer in Kretschmann configuration is analyzed theoretically using the transfer matrix method. Numerical results show that upon suitable optimization of thickness of Ag-Pt layers and the number of layers of BP and graphene, sensitivity as high as 412°/RIU (degree/refractive index unit) can be achieved for p-polarized light of wavelength 633 nm. This performance can be tuned and controlled by changing the number of layers of BP and graphene. Furthermore, the addition of graphene and heterostructures of black phosphorus not only improved the sensitivity of the sensor but also kept the FWHM of the resonance curve much smaller than the conventional sensor utilizing Au as plasmonic metal and hence improved the resolution to a significant extent. We expect that this new proposed design will be useful for medical diagnosis, biomolecular detection, and chemical examination.
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