Plasmonics最新文献

Tin sulfide, particularly in its π-phase with a cubic crystal structure, has demonstrated significant potential for use in flexible photodetector applications due to its unique optoelectronic properties. However, its performance is often limited by low photocurrent and, consequently, low responsivity. This study addresses this challenge by introducing a novel approach to enhancing photodetector performance through copper doping. A thin film of copper-doped tin sulfide (SnS: Cu) was grown on a flexible polyester substrate using the cost-effective and straightforward chemical bath deposition (CBD) technique. The photoresponse measurements demonstrated an increase in responsivity of approximately 56 times compared to what was previously reported for undoped SnS thin films in our earlier study. Furthermore, the present photodetector exhibited a strong response across a wide range from UV to near-infrared illumination. X-ray diffraction (XRD) confirmed the preservation of the cubic SnS phase. Field emission scanning electron microscopy (FE-SEM) revealed a homogeneous, quasi-spherical grain structure. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of Cu in the film, and the systematic shift of XRD peaks toward higher diffraction angles indicates that Cu is incorporated into the SnS lattice, consistent with substitutional doping. The optical measurements indicated a bandgap of 1.44 eV. The responsivity (R) and detectivity (D) were also calculated at 380 nm, 750 nm, and 850 nm. These findings underscore the potential of Cu-doped SnS thin films as next-generation flexible optoelectronic devices.

This study presents kinds of Kretschmann-configured surface plasmon resonance (SPR) biosensors employing copper (Cu), nickel (Ni), and black phosphorus (BP) for the detection of Mycobacterium tuberculosis (MTB) in human blood plasma, with the goal of enabling early diagnosis and reducing tuberculosis (TB)-related mortality. The performance of the proposed sensors is analyzed using the transfer matrix method in conjunction with the angular interrogation technique at a wavelength of 632.8 nm. The SPR angle of healthy blood plasma differs from that of plasma infected with MTB. The proposed biosensor operates by quantifying the shift in the SPR angle, enabling the identification of different stages of MTB infection. Initially, SPR biosensors with monometallic layers are investigated and optimized by employing prism coupling with varying refractive indices and systematically tuning metal layer thicknesses. Building on this, bimetallic layer architectures are explored using a CaF₂ prism, focusing on two stacking sequences: Cu/Ni and Ni/Cu. Subsequently, BP capping layers are incorporated into both bimetallic configurations. For the Cu/Ni configuration, BP capping does not improve sensitivity but significantly increases the figure of merit (FoM), reaching an ultrahigh value of 20,210 /RIU after optimization, with a moderate sensitivity of 117°/RIU. In the case of the Ni/Cu configuration, the integration of BP enhances the overall performance of the biosensor, achieving a high sensitivity of 576°/RIU and a high FoM of 303/RIU. These results demonstrate the potential of the proposed BP-capped bimetallic SPR biosensors as competitive platforms for MTB detection.

High-sensitivity sensor is of great significance in chemical and biological detection. Here, a high-performance plasmonic sensor based on a double-lobe cavity and rectangular-arc cavity structure is investigated by finite element method. Simulation results show that two independently tunable Fano resonances and one Lorentzian peak can be observed in the transmission spectrum, which can be flexibly regulated by adjusting the structural parameters. In addition, the second Fano peak can be adjusted by applying external pressure. These characteristics make our system convenient for use in high-sensitivity refractive index and optical pressure sensors with a maximum sensitivity of 2900 nm/RIU and 4.91 nm/MPa and can be enhanced up to 4200 nm/RIU and 29.28 nm/MPa, respectively, due to the gap plasmon excitation by adding a metal baffle. Our results demonstrate that this novel structure exhibits superior sensing performance, which can offer valuable insights for future advancements in the fields of integrated photonics devices and nanosensors.

In order to cope with the difficult problem of low sensitivity detection of low concentration samples and realize the high sensitivity detection of target analytes, a bifunctional sensor was designed in this study by combining the high quality factor (Q-factor) characteristic of Fano resonance with the advantage of the wide dynamic range of plasmon-induced transparency (PIT) effect. By introducing an asymmetric structure to break symmetry, the sensor is able to induce the generation of both PIT effect and Fano resonance effect in a single device, which further enhances the comprehensive detection performance of the sensor. Finite-element simulations reveal that the PIT window achieves a maximum sensitivity of 2.84 THz/RIU, while the transmission peak influenced by Fano resonance exhibits a Q-factor of 18.06 and a figure of merit (FOM) of 10.44 RIU⁻¹. Furthermore, by adjusting the structural parameters, the flexible switching of bifunctionality can be realized, which significantly enhances the accuracy of the substance detection and the range of sensing applications. The results show that the design incorporates the excellent characteristics of Fano resonance and PIT effect to achieve the high sensitivity requirement of the sensor and successfully overcomes the performance limitation of the single function of the traditional sensor.

This study presents a theoretical framework for achieving subwavelength atomic localization using surface plasmon polaritons (SPPs) in a four-level atomic system. By exploiting the strong field confinement and enhanced near-field effects of SPPs, we demonstrate high-precision atom positioning through quantum interference phenomena. The proposed model utilizes a combination of probe and control fields to generate spatially dependent absorption profiles, enabling atom localization with nanometer-scale resolution. Numerical simulations reveal distinct localization patterns dependent on phase modulation and detuning parameters, with peak resolutions reaching (lambda /20). The interaction between SPPs and atomic states is shown to overcome traditional diffraction limits while maintaining robust coherence properties. These results suggest new possibilities for quantum control at the nanoscale, with direct applications in atom trapping, nanolithography, and plasmon-enhanced spectroscopy. The analysis further identifies optimal conditions for minimizing decoherence effects while maximizing spatial resolution in plasmonic nanostructures.

Phenol is an important source of organic pollution in the environment, which can cause serious damage to human health and ecosystems. Therefore, it is crucial to develop sensitive, accurate, and rapid methods for detecting phenol. Herein, boron-doped carbon dots (CD_B) were used as a probe to construct a resonance Rayleigh scattering-energy transfer (RRS-ET) sensor. CD_B was prepared quickly by a normal pressure microwave irradiation method, and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy (IR) and other techniques. The characterization results show that the prepared CD_B has good water solubility and stability. Under NH₄Cl-NH₃·H₂O buffer conditions, phenol reacts with 4-aminoantipyrine (AP) to form receptor of indole aminoantipyrine (IA) that can be adsorbed on the donor CD_B surface to exhibit RRS-ET effect, and it makes the RRS peak intensity decreased linearly at 495 nm. Under the optimized conditions, the decreased RRS intensity is linear to phenol concentration in the range of 2.5 × 10⁻²–8.00 μg/mL, with a detection limit of 9 × 10⁻³ μg/mL. The prepared sensor showed good selectivity, high sensitivity, wide linear range, low detection limit, and good repeatability. The results of the detection of phenol in waste water are satisfactory, and the recovery is 99.8–107% with the relative standard deviation (RSD) of 2.48–3.93%, indicating the good feasibility of the established method in waste water sample analysis.

In this article, we design a composite groove structured plasmonic resonator with multiple excitation modes. We investigate performance of resonators via key parameters such as feeding method, S parameter, coupling efficiency, quality factor Q, and figure of merit (FoM). The resonator exhibits extremely sensitive to the permittivity covering its surface, based on which we propose a real-time high-sensitivity sensor for permittivity detection. The sensitivity of the LCPR sensor peaks at 435 MHz/RIU (for materials with a permittivity of 1–2) and still reaches a remarkable level of 315 MHz/RIU for materials with a permittivity of 2–4. Additionally, we incorporate slots to modify the sensor. When two slots are symmetrically introduced around the microstrip lines, the FoM value of the quadrupole mode substantially increases from 241 to 534, representing a 122% improvement, while the sensitivity remains virtually unchanged at 307 MHz/RIU. The sensor, fabricated with standard printed circuit board (PCB) technology, combines low cost, high usability, and immense potential for microwave non-destructive testing, thanks to its exceptionally dielectric sensitivity.

This study aims to synthesize Ag@TiO₂ core–shell nanoparticles using a two-stage pulsed laser ablation method for potential biomedical applications. The nanoparticles were produced in dimethylformamide (DMF) and characterized through UV–Vis spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and atomic force microscopy. The average particle sizes were determined to be 27.6 nm for silver nanoparticles (AgNPs), 43 nm for titanium dioxide nanoparticles (TiO₂ NPs), and 33 nm for Ag@TiO₂ core–shell NPs. Antibacterial assays demonstrated that Ag@TiO₂ NPs had the most significant antibacterial activity, showing inhibition zones of 24.4 mm against Pseudomonas aeruginosa and 30.5 mm against Streptococcus mutans at a 100% concentration. Furthermore, molecular docking studies revealed that Ag@TiO₂ NPs exhibited a binding energy of − 6.83 kcal/mol and an inhibition constant (Ki) of 9.91 µM, while TiO₂ NPs showed a binding energy of − 2.36 kcal/mol with a Ki of 18.69 mM. This suggests that Ag@TiO₂ interacts more effectively with the target proteins in silico. These results indicate that Ag@TiO₂ core–shell NPs are promising candidates for antibacterial applications, highlighting the importance of their structural design in enhancing bioactivity.

Metallic nanoparticles (NPs) are considered as promising candidates for solar energy harvesting owing to their strong localized surface plasmon resonance (LSPR), which supports pronounced optical absorption in the visible to near-infrared (NIR) spectral range. However, the inherently narrow spectral bandwidth of conventional metallic particles poses a significant challenge for their effective integration into direct absorption solar collectors (DASCs). In this study, we introduce SiO(_{2})@Pt core–shell nanoparticles as an advanced nanofluid platform, engineered to achieve broadband and enhanced optical absorption that aligns well with the AM 1.5 solar spectrum, thereby maximizing solar-to-thermal energy conversion efficiency. For evaluation, we employ 3-D computational modeling framework using Full-wave field analysis based on finite element method (FEM) to explore optical absorption properties to estimate solar energy efficiencies of plasmonic nanofluids. The albedo factor of the SiO(_{2})@Pt nanomaterials is significantly reduced, resulting in enhanced optical efficiency due to minimized radiative losses. Our results show that solar-weighted absorption efficiency (A(_{m})) of SiO(_{2})@Pt-based nanofluids is enhanced over 98% at very low volume fractions (1.0 (times ) 10(^{-5})) and improved the performance of DASC. Furthermore, in our comparative analysis, the investigated SiO(_{2})@Pt nanostructures demonstrate superior A(_{m}) value (>15%) relative to SiO(_{2})@Au counterparts, indicating their enhanced suitability for solar energy harvesting applications. These findings indicate that adjusting the proper geometric parameter of SiO(_{2})@Pt nanoparticles provides a novel approach to harvesting solar energy flux under optimal conditions.

The study presents a theoretical and computational study of a ZBLAN fiber-based SPR sensor in the NIR region of wavelength. Malignant liver tissues are considered as analytes, and the analysis is carried out under the phenomenon of optimum radiation damping (ORD). The sensor architecture incorporates an amorphous silicon (a-Si) substrate and silver metal (Ag) along with tellurium dioxide (TeO₂) as an absorption enhancement layer. Utilizing the dynamic nature of ORD, the quantitative analysis is carried out to observe the contribution of individual layers, their respective thicknesses, and operating wavelength towards absorption enhancement and optimization of figure of merit (FOM). The results are further explained in terms of physical concepts such as power loss, field enhancement, and Rayleigh scattering in the sensors. The systematic optimization of thickness and wavelength led to a maximum FOM of 15,810 RIU⁻¹ with an extremely small FWHM (width of spectrum) of 0.012°. The calculated power loss ratio (PLR) is 6.039 with combined performance factor (CPF) of 92337 μm⁴/RIU. After optimization, the PLR enhances by nearly five times to the initial values. A high PLR and FOM values show ultrasensitive detection, while a small FWHM shows well detectable sensing of malignancy in liver tissues. To the best of our knowledge, the exploitation of ORD for the detection of liver malignancy using ZBLAN fiber, NaF cladding, and an a-Si/Ag/TeO₂ heterostructure has been explored for the first time.