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Gold-Film-Thickness Dependent SPR Refractive Index and Temperature Sensing with Hetero-Core Optical Fiber Structure
摘要： A simple hetero-core optical ?ber (MMF-NCF-MMF) surface plasmon resonance (SPR) sensing structure was proposed. The SPR spectral sensitivity, full width of half peak (FWHM), valley depth (VD), and ?gure of merit (FOM) were de?ned to evaluate the sensing performance comprehensively. The e?ect of gold ?lm thickness on the refractive index and temperature sensing performance was studied experimentally. The optimum gold ?lm thickness was found. The maximum sensitivities for refractive index and temperature measurement were obtained to be 2933.25 nm/RIU and ?0.91973 nm/? C, respectively. The experimental results are helpful to design the SPR structure with improved sensing performance. The proposed SPR sensing structure has the advantages of simple structure, easy implementation, and good robustness, which implies a broad application prospect.
关键词： hetero-core ?ber structure,optical ?ber sensor,surface plasmon resonance,refractive index sensing,temperature sensing
更新于2025-09-19 17:13:59
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The Influence of Structural Parameters on the Surface Plasmon Resonance Sensor Based on a Side-polished Macrobending Plastic Optical Fiber
摘要： In this paper the influences of the structured parameters, namely, metal layer thickness, polished depth, macrobending radius and polished angle on the refractive index sensing performances for the side-polished macrobending plastic optical fibers (POFs) based surface plasmon resonance (SPR) sensors were investigated. A simple and controllable rotary grinding technique was introduced to fabricate the proposed sensor. The performances of sensitivity, resolution and full width at half maximum (FWHM) were evaluated. The results have demonstrated that the SPR sensor performances could be improved by changing the structural parameters, and the highest sensitivity obtained was 4793.1 nm/RIU when the external refractive index was 1.410. The proposed POFs based SPR sensors are easy fabrication, robust, and compact in size, which are useful for chemical and biological sensing.
关键词： plastic optical fibers,side-polished macrobending structure,Fiber optic sensors,surface plasmon resonance
更新于2025-09-19 17:13:59
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Single-shot Measurement of THz pulses with sub-picosecond resolution and Megahertz acquisition rates
摘要： We experimentally demonstrate a surface-plasmon-resonance-based sensor capable of detecting polysaccharide molecules, such as Xanthan gum. Experimental results demonstrate that by attaching Concanavalin A to the gold nanothin-film chip of the sensor, a linear response of the change in reflected optical power to the dissolved Xanthan gum concentration is observed, demonstrating the ability of the developed sensor to detect Xanthan gum concentrations up to 0.22 g/L.
关键词： optical sensors,desalination,xanthan gum,Biosensor,surface plasmon resonance
更新于2025-09-19 17:13:59
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Plasmonic-Active Nanostructured Thin Films
摘要： Plasmonic-active nanomaterials are of high interest to scientists because of their expanding applications in the field for medicine and energy. Chemical and biological sensors based on plasmonic nanomaterials are well-established and commercially available, but the role of plasmonic nanomaterials on photothermal therapeutics, solar cells, super-resolution imaging, organic synthesis, etc. is still emerging. The effectiveness of the plasmonic materials on these technologies depends on their stability and sensitivity. Preparing plasmonics-active nanostructured thin films (PANTFs) on a solid substrate improves their physical stability. More importantly, the surface plasmons of thin film and that of nanostructures can couple in PANTFs enhancing the sensitivity. A PANTF can be used as a transducer for any of the three plasmonic-based sensing techniques, namely, the propagating surface plasmon, localized surface plasmon resonance, and surface-enhanced Raman spectroscopy-based sensing techniques. Additionally, continuous nanostructured metal films have an advantage for implementing electrical controls such as simultaneous sensing using both plasmonic and electrochemical techniques. Although research and development on PANTFs have been rapidly advancing, very few reviews on synthetic methods have been published. In this review, we provide some fundamental and practical aspects of plasmonics along with the recent advances in PANTFs synthesis, focusing on the advantages and shortcomings of the fabrication techniques. We also provide an overview of different types of PANTFs and their sensitivity for biosensing.
关键词： localized surface plasmon resonance (LSPR),plasmonics,gold nanostructures,biosensing,thin film,lithography,nanohole array,nanofabrication
更新于2025-09-19 17:13:59
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Photothermal Effect in Plasmonic Nanotip for LSPR Sensing
摘要： The influence of heat generation on the conventional process of LSPR based sensing has not been explored thus far. Therefore, a need exists to draw attention toward the heat generation issue during LSPR sensing as it may affect the refractive index of the analyte, leading to incorrect sensory conclusions. This manuscript addresses the connection between the photo-thermal effect and LSPR. We numerically analyzed the heat performance of a gold cladded nanotip. The numerical results predict a change in the micro-scale temperature in the microenvironment near the nanotip. These numerical results predict a temperature increase of more than 20 K near the apex of the nanotip, which depends on numerous factors including the input optical power and the diameter of the fiber. We analytically show that this change in the temperature influences a change in the refractive index of the microenvironment in the vicinity of the nanotip. In accordance with our numerical and analytical findings, we experimentally show an LSPR shift induced by a change in the input power of the source. We believe that our work will bring the importance of temperature dependence in nanotip based LSPR sensing to the fore.
关键词： refractive index,electromagnetic heating,localized surface plasmon resonance,optical fiber sensors,nanotip
更新于2025-09-19 17:13:59
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Influence of Design Parameters on Multilayered Nanoplasmonic Structures in Modified Kretschmann-Raether Configurations
摘要： Surface Plasmon Resonance (SPR) technique has been of recent interest in many fields such as biological and chemical sensing, defense-related applications, etc. The introduction of graphene sheet (metal-like optical properties) over a thin-film layers plays a significant role in generating SPR. Different nanoplasmonic structures like Coupled Waveguide SPR (CWSPR) and Long Range SPR (LRSPR) are considered with modified Kretschmann-Raether configurations for different wavelengths in visible range for plasmonic sensors application. Characteristic Transfer Matrix (CTM) method in MATLAB environment is employed to obtain the theoretical results of LRSPR-based nanoplasmonic structures. Based on different compositions, minimum reflectivity as obtained is reported here. Due to the incorporation of additional graphene thin layer, keeping the angle of incidence constant, the percentage of reflectivity is being increased significantly, thereby reducing the transmission within the layers. With the variation of thickness, refractive index of different layers as well as wavelength of the LASER source, one may optimize the structures to obtain best possible performance.
关键词： Plasmonics,Surface Plasmon Resonance,LRSPR,Plasmonic Sensors,Sensitivity,CWSPR,Kretschmann-Raether Configuration,Figure of Merit
更新于2025-09-19 17:13:59
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Cold substrate method to prepare plasmonic Ag nanoparticle: deposition, characterization, application in solar cell
摘要： In this study, the surface plasmon effects of the Ag nanoparticle were investigated depending on the substrate temperature and coating time. Deposition procedure for the Ag coating was the vacuum deposition at low substrate temperature (< 300 K) instead of the commonly used the vacuum deposition at high substrate temperatures. The Ag thin films were deposited on n-type Si, glass and solar cell with safety glass substrates. The structural and optical characteristics of the Ag thin films prepared on Si and glass substrates were investigated. The Ag thin films had a polycrystalline structure with cubic phase. The (111) preferred orientation for 300 K substrate temperature was changed to (200) after 200 K substrate temperature. Homogeneous nano-sized Ag particles on Si were obtained at the 150–200 K temperature range. Optical measurements were performed for the Ag thin films prepared on glass substrates. According to reflectance measurements, plasmon resonance effect of the Ag nanoparticles was observed around 435–540 nm. The Ag nanoparticles prepared on solar cell at low substrate temperature increased the solar cell efficiency for all coating time because the nanoparticle size and shape were not changed significantly with the coating time. However, the Ag thin films prepared at high substrate temperature decreased device efficiency with the increasing coating time.
关键词： Surface plasmon resonance,Ag nanoparticle,Vacuum evaporation,Solar cell,Cold substrate
更新于2025-09-19 17:13:59
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Reconfigurable Surface Plasmon Resonance Photodetector with a MEMS Deformable Cantilever
摘要： Plasmonic photodetectors have many useful characteristics, such as wavelength- or polarization-specific photodetection. Although reconfigurable plasmonic structures have been intensively studied, reconfiguration of the optical characteristics of a plasmonic photodetector has not yet been reported. Here, we report a gold diffraction-grating-type plasmonic photodetector that reconfigures its optical characteristics with a MEMS deformable cantilever. By reconfiguring the photodetector characteristics using an angular scan of the cantilever over ?21 ~ 21 degrees, the peak shifts of the photocurrent signal waveform are found to depend on the wavelength over 1200 nm ~ 1500 nm, which is consistent with SPR theory. The proposed reconfigurable plasmonic photodetector allowed us to obtain spectroscopic information of the light in a demonstration experiment.
关键词： Schottky-barrier,Surface Plasmon Resonance,MEMS,Near-infrared light,Spectrometer,Photodetector
更新于2025-09-19 17:13:59
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Influence of H2 Atmosphere Annealing on Plasmonic Properties of Cu-Containing Silica Films Sputtered on Amorphous Silica
摘要： Copper-doped silica films have been deposited on amorphous silica (fused quartz) by magnetron co-sputtering. The resulting films were characterized for copper loading/thickness by Rutherford backscattering spectrometry, and the optical properties were evaluated by absorption and photoluminescence spectroscopies. The films were subjected to thermal treatment under a 5% H2?95% Ar-reducing atmosphere and further evaluated for surface plasmon resonance (SPR) characteristics. In addition, the occurrence of Cu nanoparticles (NPs) was evaluated by transmission electron microscopy. It is indicated that the films have effective permeability for H2, and consequently, the reduction of ionic copper takes place supporting the nucleation and growth of Cu NPs. Interestingly, along with the increase in absorption intensity of Cu NPs, the processing leads consistently to significant blue shifts in the SPR peaks. Absorption spectra were then simulated by Mie theory calculations for dielectric-embedded Cu NPs in an effort to understand the influence of particle size and medium refractive index on the SPR.
关键词： Thin films,Surface plasmon resonance,Optical materials
更新于2025-09-19 17:13:59
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Gold Nanoearbuds: Seed-Mediated Synthesis and the Emergence of Three Plasmonic Peaks
摘要： We demonstrate the first successful synthesis of reasonably monodisperse and single crystalline gold nano-earbuds (Au NEBs) using a binary surfactant mixture of cetyltrimethylammonium chloride (CTAC) and benzyldimethylhexadecylammonium chloride (BDAC) in a seed-mediated growth method. We have focused on the key chemical parameters behind the formation and growth of Au NEBs to result in tunable dimensions (lengths 37-77 nm; widths 4-6 nm and aspect ratios 7-19), as a consequence of which the longitudinal surface plasmon resonance (LSPR) peak could be tuned beyond 1200 nm. The achievement of LSPR beyond 1200 nm while maintaining the dimension well below 100 nm is a challenging accomplishment in the realm of 1D Au nanostructures. This earbud-like morphology additionally exhibits three plasmonic peaks, rather uncommon for 1D nanostructure, which were analyzed theoretically based on finite element method. The new resonance peak of Au NEB was assigned as an additional longitudinal mode intensified by the bulbous ends as well as the high-aspect ratio, thereby providing conclusive evidence that it is indeed a new morphology.
关键词： Au nano-earbud,Seed-mediated growth,Surface plasmon resonance,1D nanostructure,3D finite element method
更新于2025-09-19 17:13:59