Surface Plasmon Resonance Structure Research Articles

Manipulating photonic spin Hall split based on nonlinear effect and surface plasmon resonance

In this work, we present a surface plasmon resonance (SPR) structure containing AuAl2 and a nonlinear Kerr medium. Based on the modulation of the refractive index of the Kerr medium by pumped light, we analyze the effects of the SPR structure and pumped light on the photonic spin Hall effect (PSHE). The numerical results indicate that the thickness of the AuAl2 exerts a profound impact on the SPR, while the intensity of the pump light (Ip) exerts a significant influence on the resonance angle. The transverse shift (TS) is very sensitive to the refractive index (RI) of the sensing layer after increasing through the SPR. Furthermore, it is observed that the sign of the TS of the PSHE can be modulated according to Ip within a specific angle of incidence. In light of these findings, we put forth a novel optical signal modulation and RI sensing scheme based on PSHE. Our study provides a new mechanism for practical applications of PSHE in optical communication and precision measurement.

Four-Layer Surface Plasmon Resonance Structures with Amorphous As2S3 Chalcogenide Films: A Review.

The paper is a review of surface plasmon resonance (SPR) structures containing amorphous chalcogenide (ChG) films as plasmonic waveguides. The calculation method and specific characteristics obtained for four-layer SPR structures containing films made of amorphous As2S3 and As2Se3 are presented. The paper is mainly based on our previously obtained and published scattered results, to which a generalized point of view was applied. In our analysis, we demonstrate that, through proper choice of the SPR structure layer parameters, we can control the resonance angle, the sharpness of the SPR resonance curve, the penetration depth, and the sensitivity to changes in the refractive index of the analyte. These results are obtained by operating with the thickness of the ChG film and the parameters of the coupling prism. Aspects regarding the realization of the coupling prism are discussed. Two distinct cases are analyzed: first, when the prism is made of material with a refractive index higher than that of the waveguide material; second, when the prism is made of material with a lower refractive index. We demonstrated experimentally that the change in reflectance self-induced by the modification in As2S3 refractive index exhibits a hysteresis loop. We present specific results regarding the identification of alcohols, hydrocarbons, and the marker of E. coli bacteria.

Graphene Multi-Frequency Broadband and Ultra-Broadband Terahertz Absorber Based on Surface Plasmon Resonance

When surface plasmon resonance (SPR) occurs, the incident light is absorbed by the surface of the SPR structure, thus minimizing the intensity of the reflected light. Therefore, the SPR method is adopted in this paper to achieve perfect absorption of the absorbent. In this paper, we first propose a multi-frequency broadband absorber structure based on graphene SPR, which uses the continuous resonance of patterned graphene surface plasmon in the frequency spectrum to form a multi-frequency broadband absorption. In this simulation, a sandwich-stack structure was adopted, whereby the patterned graphene is situated on top of the SiO2 layer and the metal layer. The broad-band absorption bands of the absorber were obtained as 4.14–4.38 THz, 5.78–6.36 THz, and 7.87–8.66 THz through the analog simulation of finite-difference time-domain method (FDTD) solutions. Then, based on the multi-layer resonant unit structure, through the superposition and combination of absorbing units responding to different frequency bands, the perfect absorption of ultra-wideband is achieved. The data results illustrate that the total absorption bandwidth of the absorber is 2.26 THz, and the relative absorption bandwidth Bw is equal to 28.93%. The electric field in X-Y direction of the absorber in the perfect absorption band is analyzed, respectively, and the dynamic tunability of the absorber is studied. Finally, we studied whether the absorbing structure still has efficient absorption characteristics for the two polarization modes when the incident angle is changed from 0° to 70°. The structure model proposed has potential value for application in terahertz photoelectric detection, filtering, and electromagnetic shielding.

Enhanced Goos-Hänchen Shift of SPR Sensor with TMDCs and Doped PANI/Chitosan Composites for Heavy Metal Ions Detection in Aquatic Environment

A novel surface plasmon resonance (SPR) sensor with transition metal dichalcogenides (TMDCs) and polyaniline (PANI)/chitosan composite for detection of heavy metal ions in an aquatic environment is proposed and analyzed. A novel Goos-Hänchen (GH) shift sensing scheme based on TMDCs and PANI/chitosan structure is proposed. The theory shows that the GH shift can be significantly enhanced in the SPR structure silver (Ag), TMDCs, and PANI/chitosan heterostructures. The refractive index of Cu2+ ion is 1.3516, and the maximum GH shift of the hybrid structure of Ag-MoSe2-PANI/chitosan is−2067 λ at resonance angle 69.19° with MoSe2 4 layers and PANI/chitosan 123 nm. When different Cu2+ ion concentrations are added into the sample layer, the refractive index of the sample and GH shift of the SPR sensor will change. The maximum sensitivity of 2.425 × 106 λ/RIU is obtained by Ag-WSe2-PANI/chitosan structure, which is 463.42 times higher than the traditional SPR Ag film and 112.84 times higher than Ag-PANI/chitosan structure. Therefore, the configuration with GH shift provides a new development direction for the detection of heavy metal ions in an aquatic environment.

High performance SPR biosensor using Cu-Pt bimetallic layers and 2D materials

In this present paper, we propose a surface plasmon resonance(SPR)sensor having better performance parameters based on Kretschmann configuration. The proposed SPR sensor is a modified Kretschmann configuration comprised of BK7 prism-Cu-Pt-Graphene/BP/WS2. The bimetallic layer provides consistent enhancement of sensitivity over other SPR structures. Extensive numerical analysis based on transfer matrix theory has been performed to characterize the sensor response considering sensitivity, full width at half maxima (FWHM), detection accuracy(DA), quality factor(QF) with other conventional reported SPR sensor. We have also analyzed the electric field intensity enhancement factor(EFIEF) for the proposed SPR sensor. We have found that maximum sensitivity of 309deg/RIU corresponds to the four layer of BP configuration. We believe that this proposed SPR sensor could find the new platform for the chemical examination, medical diagnosis, gas detection and biological detection.

Investigation of high-order resonant modes for aluminium nanoparticles (arrays) using the finite-difference time-domain method.

The optical properties of aluminum nanoparticles are simulated and calculated using the finite-difference time-domain (FDTD) method. Our research has given a comprehensive explanation of how the substrate's dielectric coefficients impact the surface plasmon resonance effect. Furthermore, it offers valuable insights into the role of substrate materials with different dielectric coefficients in modulating the surface plasmon resonance effect of aluminum nanoparticles. The simulation demonstrates the high sensitivity of the structure's surface plasmon resonance (SPR) to the particle size of aluminum nanoparticles. Primarily due to the short-wavelength resonance characteristics, as the particle size increases in the presence of a substrate, there is an overall red shift in the peak position compared to the case without a substrate. A non-metallic kind of substance, which is weakly coupled to the aluminum nanoparticles, has weak electric field enhancement; nevertheless the metal substrates confer significant electrically powered field enhancement to the system, and the height of the particles placed on the substrate also affects the SPR properties of the structure. For various specific needs or possible applications requiring different characteristic peaks, the SPR properties of the aluminum nanoparticle-substrate structure can be tuned by particle size and height.

Modeling of surface plasmon resonance biosensor based on Ag/BiFeO3/Ni using 2D nanomaterial perovskite MAPbBr3

In the present work, the sensing performance analysis of a surface plasmon resonance (SPR) sensor for biological and chemical applications is reported. The structure studied consists of a silver nanofilm, the hybrid nanostructure of bismuth ferrite material (BiFeO 3 ), and a nickel nanofilm covered by a layer of perovskite CH 3 NH 3 PbBr 3 (MAPbBr 3 ) nanomaterial. Our analyses are based on the finite element method (FEM) and a monochromatic excitation of wavelength 633 nm. We numerically analyzed performance parameters such as angular sensitivity, sensitivity enhancement, factor of merit (FoM) and electric field distribution. We have shown that the proposed SPR biosensor exhibits very good detection performance in terms of sensitivity and FoM. Compared with the conventional SPR structure, the 2D nanomaterials have excellent properties, such as stronger absorption capacity, which improves the biological and chemical sensing ability of the sensor. The sensitivity and FoM of the optimized biosensor reaches 408 deg/RIU with 240% enhancement, and 93.12 RIU −1 with 138.78% improvement respectively, when the perovskite material layer covered the BK7/Ag/BiFeO 3 /Ni hybrid nanostructure; for a 0.005 RIU variation in the refractive index of the sensing medium. Therefore, our proposed design and study would be practically suitable for bio/chemical sensing and in biomedical application has excellent performance, with the available fabrication technologies. • We proposed a SPR nanostructured as a high multi-functional detection biosensor by the MAPbBr 3 perovskite nanomaterial layer: BK7/Ag/BiFeO 3 /Ni/MAPbBr 3 . • The optimized nanostructure shows the highest angular sensitivity of 408 deg/RIU. • Highest sensitivity enhancement 240% for bimetallic/nanomaterials based SPR biosensor. • This study demonstrated high FoM of 105.78 RIU {-1} with an enhancement of 171.23%.

Theoretical analysis and optimization of sensing parameters of surface plasmon resonance sensor

Abstract The right combination of substrate and metallic layer is very important to optimize the sensing parameters of surface plasmon resonance (SPR) sensors. These parameters are sensitivity, full width half maxima (FWHM) and reflectance minimum (R min) at resonance angle. It is shown in the present theoretical analysis that the right combination of substrate and metallic layer helps in reducing the number of layers in SPR multilayer structures without compromising the sensitivity of SPR sensors. The present study was performed on three layers and molybdenum disulfide (MoS2) based four layer SPR structures. Gold (Au) and silver (Ag) were used as metallic layers and dense flint (SF11) glass and barium flint (BAF10) glass were used as substrate material. The best sensitivity value was achieved with the combination of Au and BAF10 in both three and four layer structure. The optimized values of FWHM and R min were obtained using the combination of Ag and SF11 in both three and four layer structures.

Enhanced sensitivity of surface plasmon resonance biosensor for the selective detection of immunoglobin (IgG)

In this work, we propose a surface plasmon resonance (SPR) biosensor based on a hybrid structure of silicon nitride (Si3N4), molybdenum trioxide (MoO3), and graphene oxide (GO) in the Kretschmann configuration. To investigate the performance parameters of the SPR biosensor, we calculate, theoretically, the reflectance spectra of the proposed model and analysed it. The investigation of various performance parameters i.e., sensitivity, detection accuracy, and quality factor, of sensor configuration are theoretically done with the optimized thickness of silver (55 nm), silicon nitride (5 nm), molybdenum trioxide (10 nm), and graphene oxide (2.55 nm) respectively. The sensitivity, detection accuracy, and figure of merit for the proposed SPR structure are found at 301 deg./RIU, 4.01, and 133 RIU−1 respectively for the detection of IgG. Furthermore, the present SPR biosensor shows improved sensitivity as compared to the other reported works. The refractive index of the analyte changes from 1.33 to 1.37 due to adsorption of the analyte at the GO surface. The proposed sensor design can detect the small change in the refractive index of the sensing media doped with the analyte.

Optical Detection of Fat Concentration in Milk Using MXene-Based Surface Plasmon Resonance Structure.

MXene (Ti3C2Tx) has emerged very recently as an interacting material for surface plasmon resonance (SPR) configuration. It was discovered that Ti3C2Tx can facilitate the adsorption of biomolecules due to its higher binding energies, stronger interaction between matter and light, and larger surface area. In this work, a two-dimensional Ti3C2Tx and silicon layer-based SPR refractometric sensor is proposed for the sensitive and fast detection of milk fat concentration due to the high significance of this issue to people all over the world. The proposed SPR structure employs BK7 (BK7 is a designation for the most common Borosilicate Crown glass used for a variety of applications in the visible range) as a coupling prism and silver as a metal layer. The layer thicknesses and the number of Ti3C2Tx sheets are optimized for the highest performance. The highest reached sensitivity is 350 deg./RIU with 50 nm silver and 4 nm silicon with a monolayer of Ti3C2Tx, which is ultra-high sensitivity compared to the latest work that utilizes SPR configuration. The proposed SPR-based sensor’s ultra-high sensitivity makes it more attractive for usage in a variety of biosensing applications.

Modeling of High-Performance SPR Refractive Index Sensor Employing Novel 2D Materials for Detection of Malaria Pathogens.

The present work exhibits a novel design of surface plasmon resonance (SPR) biosensor, which comprises CaF2 prism, TiO2, metal (Ag/Au), PtSe2, 2D materials (graphene/transition metal dichalcogenides (MoS2/WS2)) and sensing medium, for point-of-care detection of various stages of malaria diseases. The transfer matrix method (TMM) is employed to examine the angular reflectivity of the proposed structure after judiciously optimizing the layer thicknesses and layer numbers. Phase interrogation technique is utilised to validate the position of occurrence of resonance angles. Additionally, the proposed SPR structure is designed using COMSOL Multiphysics, to assay the electric field intensity and electric field enhancement factor near the edge of 2D material-sensing layer interface. Simulation upshots revealed that the use of new class of 2D materials catapult the sensor performance to a new height compared to the traditional SPR configuration. A maximum sensitivity of 240.10°/RIU, quality factor of 78.46 RIU-1 and detection accuracy of 1.99 is attained for Ag-based SPR configuration with bilayer of WS2. Sensing parameters are compared with previously reported works to prove the superiority of the present research. Moreover, the real-time and label-free detection of malaria diseases makes the suggested sensor worth to fabricate as a SPR chip with the recent nanofabrication technologies.

Improving the Sensitivity of SPR Sensors with Au–Ag alloys and 2D Materials — a Simulation‐Based Approach

AbstractPlasmonic‐based sensing revolves around the generation of plasmons as a result of light–matter interactions. Analytical and/or diagnostic technologies based on this principle are extremely successful and popular in the bio‐medical industry due to their high sensitivity as well as real‐time and label‐free sensing capabilities. Employing 2D multilayers as the main plasmonic substrate instead of pure metals is a relatively new concept that can provide advantages for the surface plasmon resonance (SPR) sensor. In this work, the gain in sensitivity of the Au–Ag based SPR sensors is evaluated by employing 2D materials like graphene, MoS2, and WS2 in a multilayer SPR system. The simulations calculate the sensitivity of such multi‐layered SPR structures and indicate that the use of WS2 in the modified system can lead to an increased sensitivity (1.53 times) as compared to the standard Au‐based Kretschmann configuration.

Ag-Ni bimetallic film on CaF2 prism for high sensitive surface plasmon resonance sensor

Ag-Ni bimetallic film on CaF2 prism for high sensitive surface plasmon resonance sensor

U-grooved dual-channel plasmonic sensor for simultaneous multi-analyte detection

A photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed for real-time multi-analyte detection. Semicircular U-shaped slots are excavated inside the PCF to facilitate the excitation of surface plasmon polaritons by reducing the distance between the core and external analyte channels. The evanescent field is controlled via engineered scaled-down air holes. A plasmonic metal layer (gold) is deposited over the U-curved microchannel to enhance the surface plasmons. This asymmetric PCF SPR structure enables superior birefringence controllability, which results in a dominant y -polarized response in comparison to the x -polarized mode. The light-guiding and sensor performance parameters are numerically analyzed using the full vector finite element method. The proposed sensor can detect a wide refractive index (RI) range from 1.33 to 1.43. It demonstrates the maximum wavelength sensitivities of 2000 nm/RIU and 12,800 nm/RIU with sensor resolutions of 5 × 1 0 − 5 R I U and 7.813 × 1 0 − 6 R I U for channels 1 and 2, respectively. The sensor also exhibits a maximum amplitude sensitivity of 1119 R I U − 1 with a high figure of merit of 474 R I U − 1 . The simultaneous dual-analyte detection capability and highly sensitive response with a broad detection range make the proposed sensor distinct and will pave the way for miniaturized medical diagnostics and sensing applications.

Surface plasmon resonance-based optical sensor using a thin layer of plasma

We propose a surface plasmon resonance (SPR) biosensor that consists of six layers: glass prism (SF 10), chromium, metal, molybdenum disulphide, graphene, and sensing medium. A seventh layer is added between the glass prism and the chromium layer, which is a gap filled with plasma as a dielectric material. The plasma layer is expected to carry the amenity of the graphene optical characteristics and absorption ability. It is also expected to improve sensitivity of the SPR structure. The numerical calculations show that the sensitivity of the sensor is 76.11 deg/RIU (refractive index unit); without the plasma layer, it can be improved to 103 deg/RIU in the presence of 25 and 35 nm thick plasma and silver layers, respectively. The structure parameters are optimized with respect to the sensitivity. The proposed sensor can potentially be used for biological purposes.

Engineering the penetration depth of nearly guided wave surface plasmon resonance towards application in bacterial cells monitoring

Photonic techniques based on evanescent waves sensing (such as the surface plasmon resonance (SPR) method) using plasmonic and nanostructured metallic/semiconductor materials hold huge potential in biosensing and associated analysis of biomolecular interactions. However, conventional SPR suffers from low penetration depths (<300 nm), limiting the applications for the surface interactions and analysis of larger biomolecules, such as for bacteria cells with a typical size of ∼1 μm. These cases result in the measured signal being non-monotonic with concentration, making the technique unreliable for high concentrations. Infrared wavelengths can be used, but then signal contrast suffers, and the instruments required for mid-infrared or longer wavelengths are prohibitively expensive. With this in mind, we developed a “nearly” guided SPR (NGWSPR) structure to enhance the performance of these sensors by increasing penetration depth and figure of merit using wavelengths in the optical telecommunication window where off-the-shelf instruments are available at low cost. The use of this technique for monotonic detection of cultured live Escherichia coli bacterial cells is demonstrated, thus opening a pathway to utilize and promote the approach for biosensing, biomedical research and industrial applications.

Graphene oxide biohybrid layer enhances sensitivity and anticorrosive properties in refractive index sensor

Graphene-based materials are capable of enhancing the refractometric response of prism- and optical fiber-based surface plasmon resonance (SPR) sensors; however, complicated multistep and time-consuming attaching processes could limit their practical applications. Herein, for the first time, we demonstrate the immobilization of graphene oxide (GO) submicrometric sheets onto the surface of a gold-coated single-mode fiber using a coating of fungal self-assembling proteins, the hydrophobins (HFBs), as an adhesive nanolayer. Hetero-core fiber tip SPR structures used in this study, consisting of a mirrored multimode–single-mode fiber structure coated with different thin layers (a chromium layer of 3 nm and a gold layer of 30 nm on top) exhibited a refractive index sensitivity (SRI) of 1842 nm RIU−1 (RIU: refractive index unit) at a refractive index (RI) of 1.36. Self-assembly of GO over the SPR fiber tip via HFB, offered an enhancement of up to 20% in the SRI. Moreover, this HFB-GO coating prevented degradation of the Al thin film mirror caused by corrosive salt-water solutions. The process is very simple, harmless, rapid (around 15 min) and scalable, as it is mostly based on one plasma treatment, which can be performed in large chambers and two dip coating steps, in liquid baths. All these features make the use of self-assembled bio/non-bio hybrid coating a green industrial method to improve the performance of SPR fiber biosensors, if compared with traditional chemical methods. Materials applied in this technology, fungal proteins and derivatives of graphite, are sustainable and largely available.

Numerical Analysis of a Highly Sensitive Surface Plasmon Resonance Sensor for SARS-CoV-2 Detection.

In this paper, we propose a surface plasmon resonance (SPR) structure based on Kretschmann configuration incorporating layers of silicon and BaTiO3 on top of Ag for real-time detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using thiol-tethered DNA as a ligand. Extensive numerical analysis based on transfer matrix theory as well as finite-difference time-domain (FDTD) technique has been performed to characterize the sensor response considering sensitivity, full width at half maxima, and minimum reflection. About 7.6 times enhanced sensitivity has been obtained using the proposed architecture for SARS-CoV-2 detection, compared to the basic Kretschmann configuration. Notably, the structure provides consistent enhancement over other competitive SPR structures for both angular and wavelength interrogations with a figure-of-merit of 692.28. Additionally, we repeated simulations for various ligate–ligand pairs to assess the range of applicability and robust performance improvement has been observed. As a result, the proposed sensor design provides a suitable configuration for highly sensitive, rapid, noninvasive biosensing which can be useful if adopted in experimental sensing protocols.

Photonic spin Hall effect detection using weak measurement in the SPR structure using antimonene: A sensing application

In this paper, surface plasmon resonance (SPR) structure along with two-dimensional (2-D) antimonene material is proposed to enhanced the photonic spin Hall effect (PSHE). It is showed that the gold (Au) based SPR structure with antimonene can effectively improve the PSHE due to the SPR effect and the strong spin-orbit coupling of antimonene. The maximum transverse beam displacement (δH−) with the help of weak measurement technique for the H polarization can be up to 61.67 μm under the optimized thickness of Au layer, which is much greater than the previously reported δH− values as well as Au based SPR structure with graphene and MoS2. Also, SPR structure with antimonene is utilized for biosensing based on PSHE and found that the sensitivity 5468 μm/RIU, which is more than two times higher than the graphene based SPR structure. It is believed that the results may have opened a path to enhanced the PSHE in spin-based nanophotonic devices, chemical, and biological sensing.

Sodium-Based Surface Plasmon Resonances for High-Performance Optical Sensing in the Near Infrared

Surface plasmon resonance (SPR) owing to its extreme sensitivity to the refractive index of surrounding medium has been widely applied to chemical and biological sensing. However, it is difficult to realize SPR sensing simultaneously with large sensitivity and figure of merit (FOM) in a conventional prism coupling structure. In this paper, we numerically study the SPRs in a polymer-protected sodium thin film and sinusoidal nanograting based on a prism Kretschmann configuration using finite element method (FEM). In the near-infrared wavelengths, both angular and wavelength interrogation are investigated and high sensitivity (14.9 μm/RIU and 750 deg/RIU for the thin film and nanograting, respectively) and FOM (480.6 /RIU and 255.6 /RIU for the thin film and nanograting, respectively) can be achieved simultaneously. It should be noticed that the large FOM mainly originates from the narrow resonant linewidth. Additionally, our nanograting structure can support a self-reference sensing scheme, which is beneficial to realize accurate sensing. Our FEM simulations are in good agreement with the calculation by the transfer matrix method (TMM) and rigorous coupled wave analysis (RCWA). Our proposed sodium-based SPR structures do not require complex plasmonic nanostructures and are compatible with a thermo-assisted spin-coating process, which shows great potential in realizing high-performance optical sensing beyond noble metals and expands the application scope of sodium-based plasmonic devices.