Plasmonics最新文献

Plasmon-assisted graphitic carbon nitride (g-C₃N₄)–based nanomaterials have emerged as efficient photocatalysts for environmental remediation, particularly in degrading antibiotics, dyes, pesticides, and heavy metals from wastewater. The plasmonic metals, such as Ag, Au, Cu, or Pt, were formed by various routes and decorated on host matrices, including polymeric organic frames, glass composites, and 2D structures like graphene, carbon borides, carbon nitrides, and metal sulfides. The present review article presents a systematic methodology for developing plasmonic Ag and Au nanoparticle–based 2D carbon nitrides (CN)/graphitic carbon nitrides (g-C₃N₄) nanomaterials. Moreover, this review also compiles recent advances in the synthesis, structural modifications, and photocatalytic mechanisms of Ag- and Au-doped 2D carbon nitrides. The incorporation of noble metal nanoparticles enhances surface plasmon resonance, which promotes visible light absorption, bandgap tuning, and charge separation efficiency. Studies have revealed significantly improved degradation rates of pollutants up to 97% for antibiotics and over 98% for dyes, through synergistic interactions with dopants such as Cu, Pd, and rGO. Particularly, Ag-g-C₃N₄ composites achieved a reduction of up to 99.9% of Cr(VI) to Cr(III), while Pd/g-C₃N₄ nanostructures exhibited high selectivity and reusability. The review also emphasizes the impact of molecular structure on degradation efficiency and outlines future challenges in catalyst stability, scalability, and performance optimization. These findings emphasize the promise of plasmon-enhanced 2D g-C₃N₄ materials in sustainable wastewater treatment technologies.

The level of sucrose in an aqueous liquid has an extensive scope of purposes in medications, for example, food and protein safeguarding. Here, a novel PCFB has been presented to detect various sucrose levels in an aqueous solution that has an index of refraction in the scope of 1.345–1.442. The aimed PCFB includes an easy array of rectangular cavities. The capability of this detector in sensing is appraised via applying the finite element technique (FET). The effective material loss and confinement loss have been displayed extremely lower rates for the projected PCFB. Furthermore,the projected PCFB achieves an uppermost relative sensitivity of 99.514% for 70 gm/100 ml concentration of sucrose along with 98.849% core power fraction at 2.8 THz. At the same previous point, the effective area and numerical aperture are 96,483 μm² and 0.47832, respectively. These outcomes demonstrate that the planned PCFB will be used in identifying bioconstituents and poisonous chemicals effectively. Also, the simple structure confirms the possibility of fabrication by applying the current fabrication approaches without any complications.

In this paper, we propose a single polarization filter to regulate the polarization state of signal light by exploiting the high birefringence properties of photonic crystal fibers (PCFs). A two-core PCF filter based on a liquid filled with an elliptical gold hole was numerically simulated using the finite element method (FEM). The results show that the PCF filter demonstrates excellent filtering performance near the 1310 nm communication window with an air hole diameter d of 2.0 µm, a pore spacing Ʌ of 2.5 µm, a gold film thickness t of 30 nm, an elliptical hole axis d_a of 2.0 µm, and an axis d_b of 2.6 µm. The liquid of refractive index 1.36 was filled into the central air hole. The peak resonance loss strength is as high as 1008.15 dB/cm for the x-polarized mode, while it is only 39.16 dB/cm for the y-polarized mode. Moreover, the crosstalk and operation bandwidth increase with the fiber length. When the PCF transmission length reaches 400 µm, the maximum crosstalk can reach − 335.54 dB and the bandwidth can reach 550 nm. The photonic filter is expected to be widely used in optical communication, optical sensing and other fields.

A novel duplex-channel biosensor designed for simultaneous detection of cervical cancer and adrenal gland cancer is proposed here. The surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) uses a thin film of Ta₂O₅ and gold for cancer cell detection. The finite element method (FEM)-based confinement loss (C_L) analysis is used for geometrical optimization. The right and left slots are denoted by Channel 1 (Ch1), and Channel 2 (Ch2) is the label for vertically positioned top and bottom slots, respectively. Two channels are separated by a thick barrier of silica layer to prevent direct contacts between two neighboring channels such that the analytes in each channel will not mix up. Simulation results show that Channel 1 with adrenal cancer cells supports y-polarized electric field modes, whereas Channel 2 with cervical cancer cells supports x-polarized modes. For cervical and adrenal cancer cells, the sensor’s amplitude sensitivities are 1168.83 RIU⁻¹ and 394.29 RIU⁻¹, respectively, while its wavelength sensitivities are 8333.33 nm/RIU and 12,142.86 nm/RIU. The suggested sensor is a circular-shaped, dual-channel PCF sensor capable of detecting two separate analytes at the same time. The sensor uses an external sensing technique, which is affordable; liquid sample infiltration will be simpler, and it will make the sensing mechanism more convenient. With the ability to identify multiple cancer cells at once, the suggested sensor is a good fit for the biosensing applications in healthcare.

In this work, we present a surface plasmon resonance (SPR) sensor based on a BK7 prism-silver (Ag)-aluminum phosphate (({AlPO}_{4}))-2D material structure for the detection of various chemical compounds. To design this structure, Kretschmann configuration is used. The sensor’s performance is analyzed using the transfer matrix method along with the angular interrogation technique at the wavelength of 633 nm. In the proposed sensor, Ag is used as metallic layers to generate the surface plasmon on the surface of prism. Also, it provides a sharp resonance dip that leads a high resolution. However, it has a problem with getting oxidized with the environment changes; therefore, ({AlPO}_{4}) is deposited on top of Ag to address this and enhance the sensor’s performance. Moreover, 2D material is placed on ({AlPO}_{4}) to enhance the sensor’s performance further due to their exceptional properties. Finally, to sense the chemical compounds, different refractive indices from 1.4021 to 1.4072 are considered, as demonstrated with analytes like n-butyl chloride, 2-methoxyethanol, cyclopentane, methyl isoamyl ketone, and tetrahydrofuran. Results exhibit a maximum sensitivity of 432.0697°/RIU, a quality factor (QF) of 173.4662 RIU⁻¹, and a detection accuracy (DA) of 0.7459 1/RIU through the detection of various chemical samples, demonstrating excellent improvements over existing methodologies. Additionally, the standard fabrication steps were explored for the experimental feasibility of the proposed sensor. Therefore, the proposed sensor can be used to enhance the sensor performance as well as stands as a novel platform for the biological and biomedical applications.

We propose and analyze a novel plasmonic multi-resonator perfect absorber based entirely on an all-metal Cu grating structure for high-performance optical sensing applications. The design features a continuous Cu substrate with two identical grating exhibiting seven distinct narrowband resonances spanning the near-infrared region (1270–1990 nm) with absorption efficiencies exceeding 90%. With an ultra-narrow linewidth (FWHM = 0.0188 nm) and an outstanding Q-factor (≈ 10⁵), the highest-order resonance (P7) exhibits a perfect absorption value at 1991.312 nm, guaranteeing remarkable spectrum selectivity and sensing resolution. To enable tailored sensing capabilities, systematic studies reveal that adjusting geometric features such as the grating height and the spacing between gratings can precisely tune the resonance wavelength while maintaining strong absorption and narrow linewidths. Sensitivity analysis against refractive index variations in the surrounding medium indicates a high sensitivity (S ≈ 1991.311 nm/RIU), an outstanding figure of merit (FOM ≈ 1.06 × 10⁵), and a low detection limit on the order of 10⁻⁶ RIU. The absorber’s strong sensitivity to small changes in refractive index, including those caused by gas analytes such as air, helium, nitrogen, and carbon dioxide, highlights its promising potential for use in multiplexed and selective biochemical and gas sensing applications. The use of an all-metal configuration supporting multiple high-Q resonances is unique among current absorber designs. This structure combines simplicity, tunability, and multi-wavelength operation in a single material platform, offering a novel approach to achieving high-performance sensing without relying on hybrid or multilayered materials. This work advances the development of compact, tunable, and ultra-sensitive plasmonic sensors leveraging high-Q narrowband resonances in all-metal architectures.

In order to detect Giardia lamblia (GALA) in drinking water, a unique photonic crystal fiber sensor (PCFS) including a square core and rectangular air pores is reported in this work. This model has been simulated and computationally scrutinized via the finite element method (FEM). The projected model is more effective at detecting GALA in the THz range. The simulation procedure uses COMSOL Multiphysics as the simulation program and is conducted at frequencies fluctuating from 1.0 to 3.0 THz. Our PCFS design provides a higher sensitivity of 99.78% at 2.5 THz and a larger effective area of 141,211 µm² after the modeling methods. EML is also attained, and very little confinement loss is place. Furthermore, we anticipate that the exceptional photonic crystal fiber design that has been presented will be applicable, in particular, to chemical sensing in the domains of industry, biology, nano-optics, material science, and other THz technology communication sectors.

This study presents an eco-friendly approach to the synthesis and characterization of silver nanoparticles (AgNPs) utilizing a bacterial colicin extract as a reducing agent. Silver nanoparticles were successfully synthesized through the bioreduction of silver nitrate (AgNO₃) using the bioactive components of colicin under mild, non-toxic conditions. The resulting nanoparticles were characterized by UV–Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). TEM showed that AgNPs are spherical nanoparticles with a range of 5–25 nm. The biosynthesized AgNPs exhibited notable antimicrobial activity against selected pathogenic microorganisms. In addition, AgNPs exhibit anticancer activity against lung cancer cell line A549. Furthermore, molecular docking and molecular dynamics (MD) simulations were employed to investigate the interactions between AgNPs and specific bacterial receptors Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Docking studies revealed significant binding affinities between AgNPs and the active sites of these receptors, with the highest interaction observed for P. aeruginosa. MD simulations confirmed the stability and favorable energetic profiles of the AgNP–receptor complexes, supporting their promising antibacterial potential. Overall, this work demonstrates the synergistic value of green nanotechnology and computational tools in advancing antimicrobial strategies.

This work presents a dual ultra-narrowband terahertz metasurface absorber for high-sensitivity refractive index (RI) sensing. The proposed structure consists of a periodically arranged array of cross-grooved silicon disks on a silver-backed silica substrate, achieving near-perfect absorption (over 99.5%) at two resonant frequencies. The magnetic dipole resonance mode at 1.2 THz (Q = 394) and anapole mode at 1.42 THz (Q = 1069) are excited based on electromagnetic field analysis, resulting in perfect absorption for incident electromagnetic waves. The ultra-narrow bandwidths (FWHM = 3.04 GHz and 1.33 GHz, respectively) and strong field confinement are observed in the region of the cross-grooved silicon disks and silica dielectric layer. The metasurface achieves exceptional sensitivities of 114.28 GHz/RIU and 321.43 GHz/RIU and figure of merit (FOM) of 37.59 and 241.67 at resonant frequency of 1.2 THz and 1.42 THz, respectively. Structural parameters have also been studied for tuning resonance frequency and absorption efficiency (> 95%). The proposed metasurface is used to detect the concentration of glucose solution (0 ~ 465.8 mM, the corresponding RI = 1.333 ~ 1.345) to verify the sensing applications. The results demonstrate that the anapole resonance mode exhibits higher sensitivity than the magnetic dipole mode, enabling enhanced sensing performance of the metasurface-based sensor through synergistic dual-mode detection. This work presents a practical design strategy for ultra-high-Q multi-band metasurface sensors with exceptional sensitivity and FOM, promising for biosensing and environmental monitoring applications.

Whispering gallery modes (WGMs) have emerged as a unique platform to produce extreme localization and enhancement of light waves due to their high-quality (Q) factors. This study theoretically demonstrates the excitation of dark WGMs in individual elliptical dielectric disks under the normal incidence of a plane wave, where the Q factors can be pushed even higher. This is achieved by turning the dark WGM into a quasi-bound state in the continuum (QBIC) case, where the dark WGM and a bright anapole mode are involved in the interferences. By adjusting the geometric parameters of the elliptical disk, the Q factor of the QBIC-WGM can be further enhanced by more than 40% compared to the intrinsic WGM. In addition, by introducing an additional degree of freedom, namely a gap, stacked elliptical disks can be constructed to achieve QBIC-WGM, and it is found that both the response and Q factor of this QBIC mode are stronger than that of the intrinsic WGM. Our results demonstrate that by establishing a QBIC situation, the WGMs in disks can be excited with normal incidence, which is experimentally more feasible. Furthermore, the Q factors of WGMs can be pushed even higher, which could find applications in enhanced light-matter interactions.