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Surface plasmon resonance on blue GaN-based VCSEL with Al-grating
摘要： Based on the research of surface plasmon (SP) applied to Vertical-Cavity Surface-Emitting Lasers (VCSEL), we proposed a new 465 nm GaN-based VCSEL to enhance illumination by deposit Al rectangular grating onto p-i-n layer. Meanwhile, an increase in the e?ective radiated power was obtained by the control of a surface plasmon mode, which depends strongly on the structural parameters such as material, period, depth and dipole location. Compared to conventional structure, we have a 30% improvement in e?ective radiated power. Such advantages make surface Al-grating be an alternative low-cost and simple technique used in SP-coupled VCSEL for the blue range.
关键词： Finite-di?erence time-domain method,Metal grating,Surface plasmon,Vertical-cavity surface-emitting laser (VCSEL)
更新于2025-09-23 15:23:52
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Quantum regime for dielectric Cherenkov radiation and graphene surface plasmons
摘要： In this article, we propose a quantum regime for Cherenkov free-electron laser (CFEL) and surface plasmon polaritons (SPPs) excited in dielectric and multilayer graphene waveguides, respectively. This quantum regime is realized when the momentum spread induced in the interaction is smaller than the photon recoil. The discrete momentum exchange characterizing this interaction yields a significantly narrow single emission line. To determine the condition of the quantum regime, we derive an expression for the gain in the Cherenkov effect using a quantum mechanical treatment. It is assumed that the effective spread in momentum is due to the finite interaction length L (or the propagation length in the case of SPPs). For both cases, CFEL and SPPs, the effects of electron beam and waveguide parameters on the possibility of the quantum regime are studied. We conclude that the quantum regime can be basically verified at low electron beam energy (<40 keV) and at emission wavelengths in the near infrared range (<5 μm) when L is in the order of millimeters. In the case of SPPs, we also show that the feasibility to realize quantum SPPs is enhanced by increasing the chemical potential and number of graphene layers.
关键词： Quantum light,Surface plasmon polaritons,Graphene,Cherenkov radiation
更新于2025-09-23 15:23:52
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Surface Plasmon Resonance Based Highly Selective Fiber Optic Dopamine Sensor Fabricated Using Molecular Imprinted GNP/SnO <sub/>2</sub> Nanocomposite
摘要： Fabrication and characterization of a highly selective fiber optic surface plasmon resonance-based dopamine sensor using molecular imprinted graphene nanoplatelets/tin oxide (SnO2) nanocomposite have been reported. The synthesis of sensing layer has been carried out using a series of optimizations and morphological studies. The effectiveness of the sensing layer over other possible probe designs has been proved by performing control experiments for a dopamine concentration range covering the suggested level of dopamine for human being. The limit of detection (LOD) of the sensor evaluated is 0.031 μM, which is lower than the LOD values of various dopamine sensors fabricated using different methods. The specificity of the sensor for dopamine has been confirmed by performing experiments using various interferands while the stability and reusability of the sensor probe have been checked by performing experiments repeatedly for a long period of time. Apart from high sensitivity, low LOD, and fast response, the sensor can be used for remote sensing and online monitoring of dopamine.
关键词： surface plasmon resonance,SnO2 nanoparticles,optical fiber sensor,GNP/SnO2 nanocomposite,graphene,Dopamine,molecular imprinting
更新于2025-09-23 15:23:52
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An automatic multi-thread image segmentation embedded system for surface plasmon resonance sensor
摘要： In order to reduce the uncertainties associated with manual selection of regions of interest (ROIs) commonly used in Surface Plasmon Resonance (SPR) imaging system, we proposed and implemented an automatic image segmentation method in an embedded system to facilitate the potential real-time applications. Intuitive marker-controlled watershed algorithm is developed to segment ROIs (reaction, blank, and background regions) from images acquired from an experimental image SPR system. The marker assignment algorithms and pre-processing algorithms are executed in parallel by multi-threading programming on the multi-core embedded system to both real-time and good quality of segmentation. This method exhibited a good robustness in a series of ROIs segmentation test. Furthermore, the intensity response from triplicate detection of glucose standard solutions indicated a good reproducibility of data. The linear range was from 2.5 mg/mL to 20.4 mg/mL, with a correlation coefficient (R2) of 0.999 and sensitivity of 2.69 a.u./mg/mL. In conclusion, the proposed automatic image segmentation method effectively makes the measurement more precise and simplified.
关键词： Optical sensor,Surface plasmon resonance (SPR),Biosensor,Watershed algorithm,Image segmentation
更新于2025-09-23 15:23:52
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Reusable surface plasmon resonance sensor for rapid detection of Cu2+ based on modified-chitosan thin film as an active layer
摘要： In this article, a reusable surface plasmon resonance (SPR) sensor for rapid detection of copper ions (Cu2+), based on optimized silver/gold (Ag/Au) composite film modified by modified-chitosan (MCS) thin film as an active layer, was achieved. We employed a four-layer Kretchmann semi-cylindrical prism configuration and induced a reference beam into the experimental system to improve the sensitivity and stability, and investigated the cross-linking technique of CS solution, the spin coating process of MCS film, the stability of active layer, the rebirth power of SPR sensor, and the detection for trace Cu2+. The rate of swelling or dissolution of MCS film after flushing sensor chip for four times is less than 9×10?4/min, and the decline of signal value is less than 1.5% after MCS film adsorbing Cu2+ and multiple flushing. The elution and capacity rates are above 96% after five times of elution for the sensor by EDTA solution with 0.5mmol/L. Within 1-5ppm, the SPR sensor was found to possess sensitivity of 0.7271ppm?1. The LOD is 18ppb for the trace Cu2+. The present SPR sensor not only could be used in trace monitoring of Cu2+ but also could be extended to other potential applications.
关键词： Copper ions,Reutilization,Composite film,Modified-chitosan,Surface plasmon resonance
更新于2025-09-23 15:23:52
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Ultrasensitive U-shaped fiber optic LSPR cytosensing for label-free and in situ evaluation of cell surface N-glycan expression
摘要： Label-free and in situ detection of N-glycan expression on surface of cells is vital for understanding the progression of cancer. Herein, cytosensing based on U-shaped fiber optic local surface plasmon resonance (LSPR) was developed for cancer cell detection and N-glycan evaluation on cell surface. The U-shaped fiber optic LSPR has high refractive index sensitivity (RIS). Therefore, U-shaped fiber optic LSPR cytosensing afforded ultrasensitivity for cancer cell detection with the limit of detection (LOD) of 30 cells/mL and good linearity in a wide range of 1×102-1×106 cells/mL under the optimal conditions of modified AuNPs size and Con A concentration. The U-shaped fiber optic LSPR cytosensing shows more than 29 times lower limit of detection than the straight ones. More importantly, the prepared U-shaped cytosensing was applied to evaluate the N-glycan expression level on the surface of cancer cells under different concentration external stimuli of inhibitor tunicamycin (TM). Noticeably, U-shaped fiber optic LSPR cytosensing showed an acceptable reproducibility, satisfactory anti-interference and good selectivity, and was also applied in the assessment of N-glycan expression on surface of six kinds of cell lines. Therefore, the U-shaped fiber optic LSPR offers a feasible tool in biophysical research and clinical diagnosis for cancer.
关键词： Cancer cell,N-Glycan expression,Cytosensing,U-shaped fiber optic probe,Local surface plasmon resonance
更新于2025-09-23 15:23:52
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The Effect of Physical and Geometric Parameters on the Surface Plasmon Resonance Response of a Fiber Optic Biosensor: Sensitivity Analysis and Numerical Optimization
摘要： The study of the influence of optical and geometric parameters on the spectral response of the biosensor is an important step towards the optimization of these parameters. In this study, an improved SPR biosensor with a high resolution is proposed. The present SPR biosensor is based on an optical fiber that takes the place of the prism, compared with the conventional configuration, in order to simplify the detection process, overcome the stresses caused by the massive prism and obtain a reliable and efficient miniature device. The modeling procedure is based on a matrix formalism developed for the optical studies of multilayer media. We have discussed the effect of physical and optical parameters on the resonance curves, from the theoretical analysis of the transmitted power. The obtained results show that the response of the biosensor is highly dependent on these parameters. The optimum values of the length of the sensitive area, the core diameter of the optical fiber, the thickness of the metal layer and the refractive index of external environment have been determined.
关键词： Optical Fiber,Biosensors,Numerical Optimization,Surface Plasmon Resonance SPR,Sensitivity
更新于2025-09-23 15:23:52
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Design of titanium nitride coated PCF-SPR sensor for liquid sensing applications
摘要： In this paper, a titanium nitride (TiN) coated highly sensitive PCF-SPR sensor design is proposed and numerically analyzed. Titanium shows the excellent plasmonic properties in the visible and infrared regions and it has low loss and corrosion resistive nature. In this theoretical analysis, we introduce the dependencies of the confinement loss, wavelength sensitivity and amplitude sensitivity to the operating wavelength, thickness of TiN, channel width and refractive index of the measured liquid. For the proposed PCF-SPR sensor design, the high wavelength sensitivity and the refractive index resolution of ～10,000 nm/RIU and ～2.0 × 10?5 has been achieved in the refractive index (RI) range of 1.385–1.40, respectively. Even the proposed design has low amplitude sensitivity, but this proposed sensor will be used in detection of RI of chemicals, biochemical analyte with low concentrations, and highly demand in lab-on-a-chip PCF-SPR sensing probe devices.
关键词： Sensitivity,PCF,Surface plasmon resonance
更新于2025-09-23 15:23:52
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Silicon-Based Embedded Trenches of Active Antennas for High-Responsivity Omnidirectional Photodetection at Telecommunication Wavelengths
摘要： Although the use of plasmonic nanostructures for photodetection below the band gap energy of the semiconductor has been intensively investigated recently, efficiencies of such hot electron-based devices have, unfortunately, remained low because of the inevitable energy loss of the hot electrons as they move and transfer in active antennas based on metallic nanostructures. In this work, we demonstrate the concept of high-refractive-index material-embedded trench-like (ETL) active antennas that could be used to achieve almost 100% absorbance within the ultrashallow region (approximately 10 nm) beneath the metal?semiconductor interface, which is a much smaller distance compared with the hot electrons’ mean free path in the noble metal layer. Taking advantage of these ETL-based active antennas, we obtained photoresponsivities under zero bias at wavelengths of 1310 and 1550 nm of 5854 and 693 nA mW?1, respectively—values higher than most those previously reported for active antenna-based silicon (Si) photodetectors that operate at optical telecommunication wavelengths. Furthermore, the ETL antenna strategy allowed us to preserve an omnidirectional and broadband photoresponse, with a superior degree of detection linearity of R2 = 0.98889 under the light of low power density (down to 11.1 μW cm?2). The photoresponses of the ETL antenna-based device varied by less than 10% upon changing the incident angle from normal incidence to 60°. Because these ETL-based devices provide high responsivity and omnidirectional detection over a broad bandwidth, they show promising potentials for use in hot electron-based optoelectronics for many applications (e.g., Si photonics, energy harvesting, photocatalysis, and sensing devices).
关键词： hot electron,embedded,plasmon,Schottky,high-refractive-index material
更新于2025-09-23 15:23:52
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Bumpy Hollow Gold Nanospheres for Theranostic Application: Effect of Surface Morphology on Photothermal Conversion Efficiency
摘要： The combination of hollow core and rugose surface morphology is highly attractive for photoactive near-infrared (NIR) nanomaterials. Here, we present a facile pH modification to hollow gold nanosphere (HGN) synthesis to enable controlled tuning of the surface morphology from smooth to very bumpy. Unlike other methods, the synthetic protocol does not require harsh surfactants, secondary reducing agents, or organic solvents. The resultant bumpy HGNs (bHGNs) are highly monodisperse with little variation in protrusion length from particle to particle. Mechanistic studies suggest that surface rugosity is mainly controlled by the presence of free OH- ions in solution. We also present the first systematic investigation into the effect of surface morphology on the photothermal conversion efficiency (PCE) of bumpy as well as smooth HGNs, with a maximum PCE reaching 99%. Although expected to have a higher scattering component, the bHGNs retain the excellent PCE of their smooth counterparts, which may be due to efficient reabsorption of scattered light.
关键词： surface plasmon resonance,photothermal conversion efficiency,heat generation,surface morphology,hollow gold nanospheres
更新于2025-09-23 15:23:52