Plasmonics最新文献

In this work, we fabricated graphene terahertz detectors with dual-side metallic gate. Detectors using only one set of gates showed a monotonic change in responsivity as gate voltage changed, with a peak value of ~ 12 V/W within 0.1 THz, and no distinguishable response above 0.1 THz. The dominating mechanism was found to be the photo-thermoelectric (PTE) effect. Detectors using multiple sets of gates showed monotonic and non-monotonic change in responsivity as gate voltage changed, with peak responsivity of 462 V/W at 0.082 THz and 198 V/W at 2.52 THz. In the frequency ranges where the responsivity changed monotonically, the dominating mechanism was found to be the PTE effect for frequencies. In the frequency ranges where responsivity changed non-monotonically, the dominating mechanism was found to alternate between the plasmon rectification effect and the PTE effect at different gate voltage. The excitation of graphene plasmons promised non-degrading responsivity below 0.105 THz and at 2.52 THz.

Today, the advancement of suitable detectors for quick and precise discovery of explosives is a serious necessity for numerous safety and security purposes. Here, a novel trend is presented that employs a photonic crystal fiber device (PCFD) structure for the recognition of various explosives including nitroglycerin explosive (NGE), trinitrotoluene explosive (TTE), and royal demolition explosive (RDE). COMSOL Multiphysics software is employed and the finite element technique is operated to analyze the functioning of the offered PCFD. In the offered PCFD, we struggled to cover the whole fiber zone to exhaust the greatest volume of the incident waves which will boost the performance of the advanced PCFD. With ultra-high relative sensitivity of chosen explosives containing NGE (99.107), TTE (99.556), and RDE (95.940%), the offered PCFD demonstrates its extraordinary aptitudes. Furthermore, the suggested PCFD provides very low confinement loss and effective material loss values, which means tiny loss can happen. These characteristics emphasize its capability to accurately determine even the most slight modifications in the refractive index for the tested samples.

Breast cancer, a prevalent malignancy worldwide, necessitates the development of highly sensitive and specific diagnostic tools for early detection and personalized treatment. Biomarkers include routine or ordinary, novel, and potential biomolecules consisting of nucleic acids (DNA/RNA), key proteins, genes, and intact cells. Advances in biotechnology and molecular medicine have led to the identification of biomarkers for early diagnosis and therapeutic intervention, particularly through the development of novel biosensors, which hold significant clinical value. In this review article, we first present the main biomarkers involved in breast cancer. Then, the mechanism and different types of SPR techniques including traditional SPR, growth-mediated SPR, etching, and SPR imaging technologies are introduced. Furthermore, we explore various localized SPR (LSPR) biosensor designs, surface functionalization strategies, and signal transduction methods used for breast cancer biomarker detection. This review specifically mentions LSPR sensor designs, surface functionalization strategies, and signal transduction methods, indicating a focus on specific and innovative approaches within the SPR technology. We examine the performance characteristics of these biosensors, including their detection limits and selectivity, and discuss their potential for clinical translation.

Graphical Abstract

One of the most promising techniques for the study of the optical properties of dental materials is the use of surface plasmon resonance (SPR). This optical phenomenon occurs when a monochromatic light beam is incident on a conductive metallic surface. Conventional terms include a prism with a thin film coating of a noble metal, e.g. gold or silver and a 2-dimensional or dielectric material. Interaction of the light metal leads to the oscillation of electrons in the conduction band, thus inducing SPR at the metal–dielectric interface. The phenomenon can be utilized to measure various optical parameters of teeth, e.g. sensitivity and reflectance. A prototype sensor was designed and tested to evaluate the parameters using MATLAB software in combination with the characteristic transfer matrix (CTM). Various performance parameters of interest to the sensor were studied, including a full width at half maximum (FWHM) of 6.266°, a sensitivity of 190.48° per refractive index unit (deg/RIU), a figure of merit of 30.401 RIU⁻¹, and detection accuracy of 0.159 degree⁻¹. The results show that the proposed sensor is useful for biomedical applications.

High-sensitivity plasmonic refractive index sensors play a crucial role in chemical and biological detection. In this work, we propose a novel and compact sensing structure composed of a MIM waveguide coupled with an asymmetric ellipsoidal resonator. Finite element simulations demonstrate that symmetry breaking in the structure enables the excitation of multiple sharp Fano resonances along with a distinct Lorentzian resonance, significantly enriching the spectral response. Compared with conventional symmetric resonator designs, the proposed structure offers three key advantages: (1) support for multiple narrow Fano modes; (2) independent tunability of both Fano and Lorentz peaks; and (3) directional and selective spatial field distributions of coupled modes, enhancing both sensitivity and resolution. By tuning the geometric parameters, precise control over resonance wavelengths is achieved, showing excellent tunability. The structure reaches a high refractive index sensitivity of ~ 1700 nm/RIU and the FOM up to 2.13 × 10⁴. Furthermore, it exhibits pronounced spectral responses to variations in glucose and plasma concentrations, indicating strong potential for label-free biochemical sensing. This study provides a promising strategy for designing multi-channel, high-resolution plasmonic sensors and integrated photonic devices. 

Understanding how the refractive index of water changes with wavelength under different physical and chemical conditions, such as temperature or pressure, is crucial for describing the behavior of light as it travels through, reflects from, and is absorbed by water. The refractive index can act as an in situ indicator of various physical properties of liquids, such as density and pressure. Research has highlighted the influence of pressure on the refractive index at specific visible wavelengths, emphasizing the need for further exploration of these relationships. This research presents a sophisticated surface plasmon resonance (SPR) optical sensor that integrates 2D materials into a Kretschmann setup. The sensor is structured with multiple layers, including a BK7 prism, gold (Au), black phosphorus (BP), and graphene. Its performance was assessed through the finite difference time domain (FDTD) method, allowing for an in-depth analysis of crucial parameters like sensitivity. At a wavelength of 633 nm, the sensor achieved outstanding performance, with a sensitivity of 174.61 deg/RIU and a figure of merit (FOM) of 26.36 RIU⁻¹, surpassing earlier designs. These results demonstrate the sensor’s capability to measure liquid pressure, including that of water, by detecting changes in optical properties associated with varying pressures. The study shows that variations in the refractive index of water can be observed at pressures exceeding 100 or 250 MPa. Operating pressures up to 250 MPa are required for various applications, such as waterjet cutting of thick and hard materials.

This study presents an analytical investigation of terahertz (THz) generation from obliquely incident laser beams interacting with the anharmonic nanoparticles. The model incorporates the effects of nanoparticle density gradients, described by an exponential ramp profile, and the nonlinear response of nanoparticles. Numerical simulations were performed to analyze the influence of incidence angle, density gradient, interparticle spacing, and anharmonicity on THz amplitude. The results demonstrate a strong angular dependence of THz generation, with maximum amplitude at near-normal incidence. The THz amplitude decreases with the increasing slope parameter of the density ramp. The presence of a density ramp enhances THz generation. Smaller interparticle spacings result in higher THz amplitudes, emphasizing the importance of collective effects, while anharmonicity amplifies THz output by increasing the system’s nonlinearity. By exploring the effects of density gradients, inter-particle spacing, and anharmonicity, the model reveals broadband THz emission capabilities. The findings provide insights for optimizing the THz generation from nanoparticles by controlling these parameters and hold significant promise for applications in next-generation wireless communications (5 G/6 G), spectroscopic analysis, and non-invasive medical imaging, where efficient and broadband THz sources are crucial.

Plasmonics demultiplexers have several potential applications in military contexts, particularly due to their ability to manipulate light at the nanoscale and their advantages in communication and sensing technologies. Plasmonics demultiplexers represent a promising technology for military applications, enhancing communication, sensing, and intelligence capabilities. Their ability to operate at the nanoscale allows for more efficient and compact systems, which is crucial in modern military operations. As research and development in plasmonics continue to advance, their integration into military technologies could lead to significant improvements in operational effectiveness and security. Finite-difference time-domain (FDTD) as a numerical method is used to simulate the proposed plasmonic structure. This allows for the analysis of field distributions, resonance conditions, and coupling efficiencies. The applied Grey Wolf Optimization algorithm here involves updating the positions of wolves iteratively based on a mathematical equation-inspired optimized algorithm for a plasmonics demultiplexer that requires a multifaceted approach, combining simulation and design optimization. By leveraging advanced computational techniques and iterative design processes, it is possible to create highly efficient and effective plasmonic devices for a variety of applications in optical communication and sensing.

Methane, a highly flammable and explosive gas, poses significant safety risks and challenges for industrial applications. A highly sensitive sensor based on surface plasmon resonance within a photonic crystal fiber is presented and fully analyzed. This sensor measures methane concentration while providing self-calibration. The photonic crystal fiber features a D-type structure with grooves, where composite two-dimensional material film and gold films are deposited. Additionally, a methane-sensitive layer containing cryptophane-A is coated on the surface of the D-type structure. The finite element method is utilized to analyze and compare the coating of different two-dimensional materials (graphene, MoS₂, and graphene–MoS₂) on the simulation analysis of sensor sensitivity. The use of graphene–MoS₂ composite two-dimensional material not only enhances the sensing performance but also excites the double-peak effect. This double-peak effect enables the methane sensor to measure at different wavelengths, with the primary and secondary peaks calibrated against each other to improve the sensor's accuracy. The results show that the surface plasmon resonance based on photonic crystal fiber sensor with graphene–MoS₂ composite membrane has better sensing performance. The maximum wavelength sensitivity and average wavelength sensitivity reached 80 and 63.4 nm/%, respectively, over the range of methane concentrations from 0.5 to 3.5%. These properties are significantly better than those of recently reported methane sensors. Therefore, the sensor has excellent application prospects in miniature methane detection field.

This work reports on the fabrication of gold nanoparticles (Au NPs)/zirconium oxide (ZrO₂)/porous silicon photodetector for multi-wavelength detection, particularly for UV detection. This multilayer photodetector is fabricated using more than one method. Au NPs are synthesized by pulsed laser ablation in liquid (PLAL), followed by drop casting on ZrO₂ thin films prepared with (600, 800, and 1000 mJ) laser energy through pulsed-laser deposition (PLD) on a porous silicon substrate. For the first time, significant properties of this fabricated photodetector are enhanced, including gain, sensitivity, detectivity, responsivity, and quantum efficiency. X-ray diffraction results revealed that the Au/ZrO₂/PSi thin films have a crystalline structure with a face-centered cubic (FCC) phase for Au NPs, while ZrO₂ exhibit a dominant monoclinic phase. The uniform particle distribution and nanoscale size range (10–15 nm) for this composite are demonstrated by FE-SEM. High-resolution TEM shows the spherical shape of Au NPs. Furthermore, the J-V characteristic test revealed that photocurrent increased directly with light intensity. The focus here is on UV detection. The photodetector responsivity at an applied bias of 3 V increased from 0.15 to 0.17 A/W at 350 nm with an increase in laser energy from (600 to 1000 mJ), while detectivity reached its highest value of 2.5 × 10¹¹ cm Hz^0.5/W for the 600-mJ film. Quantum efficiency demonstrated better results, reaching up to 60.7% for 1000 mJ. The results of the Au/ZrO₂ photodiode indicate that the performance of the UV photodiode is enhanced with increased laser pulse energy.