Plasmonics最新文献

This research presents plasmonic metasurface-based graphene sensor for highly sensitive and label-free detection of COVID-19 biomarkers. The proposed sensor structure integrates graphene with specially engineered metasurface resonators for the detection of SARS-CoV-2 biomarkers through analysis of terahertz spectroscopic signatures. Finite element method simulations were performed to optimize the sensor design, including resonator dimensions, angle of incidence, and graphene chemical potential. The optimized sensor demonstrates a maximum sensitivity of 400 GHzRIU⁻¹, a figure of merit of 0.224 RIU⁻¹, a quality factor of 7.942, and a detection limit of 0.465 RIU. Electric field distribution analysis provides insights into the sensor’s plasmonic modes and light-matter interactions. The sensor also shows potential for 2-bit encoding applications. Compared to existing designs, the proposed sensor exhibits superior performance in key metrics like sensitivity among others. This plasmonic metasurface approach presents a promising platform for rapid, sensitive, and specific detection of SARS-CoV-2 and other viral biomarkers, with potential applications in advanced diagnostic tools and public health monitoring.

Plasmonic nanostructures continue to be the most promising alternative to hyperthermia treatment of cancer or tumors by focusing the light locally. Absorption and scattering cross-sections of 48 nanorods encompassing silver and palladium as core and gold and platinum as coating with four different aspect ratios and three different coating thicknesses were examined in an aqueous solution with finite-element method (FEM). According to the highest value of photothermal conversion efficiency (PCE) in each bimetallic compound, three Au@Ag, Pt@Ag, and Au@Pd nanorods, with aspect ratios of 4, 4, and 5, respectively; and all with a coating thickness of 1 nm; were chosen as the best ones named “A,” “B,” and “C”. Each nanorod irradiated by continuous wave (CW) laser radiation with 1 mW·μm⁻² intensity at the LSPR wavelength for 200 ns, the temperature of the nanorods increased from 37 to 82.6, 46.34, and 44.33 °C, respectively. To robustly control the temperature in time and locally, the irradiation intensity of the “A” was decreased to 0.5 mW·μm⁻², that its ambient temperature increased by 45 °C at a distance of 20 nm, which can selectively cause irreparable damage to the cancer cells. In addition, the nanorods were irradiated by pulsed laser for 200 ns periods. The results show that the bimetallic nanoparticles can convert light into heat locally.

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One significant application of this research article is enhancing the sensitivity of refractive index-based localized surface plasmon resonance (LSPR) sensor by using TiN nanostructures. The LSPR-based sensors are highly effective in detecting minute environmental changes and a crucial measure for these sensors is the refractive index sensitivity (RIS). The unique properties of TiN nanoparticles and the precision of the FDTD method drive significant interest in optimizing size and shape of TiN nanoparticles for enhanced RIS. By optimizing above mention parameters, we maximized the RIS to ~979 nm/RIU, thereby improving the performance of LSPR-based sensors. This research is vital for developing highly sensitive and efficient nitride-based LSPR-based sensors, which have applications in biomedical diagnostics, environmental monitoring, and other fields.

This study proposes the franckeite layer onto a bimetallic (Au–Cu) based sensor. The proposed sensors use CaF₂ prism, Au (39 nm), Cu (5 nm), with/without franckeite, and adsorption layer (sensing medium (SM). All the performance analysis is carried out at 633 nm wavelength. At optimized, the bimetallic layer, the remarkable sensitivity, DA, and FoM of 350.76°/RIU, 0.144/°, and 50.50/RIU are achieved, respectively. The proposed sensor’s computed electric field (EF) intensity and penetration depth (PD) are 2.11 × 105 V/m and 204.28 nm at an RI of 1.330 SM. With a quick response indicated by a significant shift in resonance angle, the suggested structure would help detect the RI between 1.33 and 1.335. A detailed comparison with the most recent publications in biomedical applications confirms the outstanding performance of the proposed SPR sensors. This comparison highlights the significant potential of the sensors in biosensing and biomedicine.

We have proposed all single-qubit logic gates with four InGaAs quantum dots (QDs) coupled to a T-type plasmonic waveguides (PWs) wherein binary qubits are encoded by frequency of photons. Our results reveal that by adjusting distance between QDs, coupling strength and frequency detuning in a proper manner, an arbitrary single-qubit gates can be achieved. We investigated schemes theoretically via the real-space approach and estimated feasibilities of a proposed one by fidelities for a variety of parameters. Under the present technology and high fidelities, our proposed schemes are feasible, opening the promising perspectives for constructing quantum computation and quantum information processing.

This paper introduces an ultrathin metamaterial absorber based on MXene, consisting of a subwavelength-sized periodic square-ring-shaped nano-cylinder operating in the visible-infrared regime. The proposed absorber consists of a three-layer standard configuration, featuring a top layer comprising a MXene nano-square cylinder, a middle dielectric material, and a bottom ground plane. It is observed that the proposed nano-absorber presents a broadband response and illustrates an absorption value of 90% across a large wavelength spectrum ranging from 400 to 2400 nm. This notable absorption is attributed to the localized surface plasmonic resonances (LSPR) induced at the top metasurface composed of periodic structures. The designed absorber exhibits a polarization-insensitive response and its due to the inherent symmetric nature of the constituent top unit cell. Furthermore, the absorber maintains stable absorption even at oblique angles up to 60°. The presented nano-absorber displays promising prospective for diverse applications, including solar cells, energy harvesting, and thermal imaging.

In this work, nickel ferrite thin films were prepared using dc reactive sputtering technique. A new geometrical configuration of the sputtered target is proposed. It includes coating of an iron target with nickel thin film with lower area and then used it as a co-sputtering target to prepare nickel ferrite thin films on glass substrates. This configuration can be considered a novel method to prepare this material with a one-step process using the same deposition system. The structural and spectroscopic characteristics of the prepared material were determined and the formation of the nanostructures within the deposited films was confirmed. The prepared nanomaterial showed high structural purity with energy band gap in the typical range.

This paper presents surface plasmon polaritons in graphene material–based reconfigurable antennae for advanced environmental monitoring applications. The antenna consists of multiple elements which are made up of graphene material. It enhances the antenna’s performance, enabling tunability and adaptability in response to environmental conditions. Additionally, the defective ground structure has been incorporated into the antenna characteristics that contribute to improving the radiation patterns and frequency selectivity. The proposed antenna is excited through a silver nanostrip feedline coupled through vias to the radiated elements. The antenna is resonating at 5.046 THz, with a bandwidth of 7.611 (mathbf{%}) (5.21–4.828 THz). The reconfigurable antenna provides an acceptable limit of directivity along with high efficiency. Here, the reconfigurability is obtained by disabling and enabling the topmost radiating elements systematically. Moreover, the resonant frequency can be adjusted by modifying the external biasing voltage applied to the graphene material. The antenna generates the higher-order ({mathrm{TM}}_{65}) mode. Furthermore, a parametric analysis has been conducted to achieve impedance matching and antenna tuning by changing the external bias voltage applied to graphene elements. The proposed reconfigurable antenna system demonstrates promising capabilities for versatile environmental sensing applications including monitoring parameters such as temperature, humidity, and pollutant levels.

A D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) is proposed. We used an open-ring channel coated with a gold film to excite the plasmonic modes. The coupling properties and sensing performance of this structure are analyzed using the finite element method. Different from the related D-shaped PCF refractive sensor, the sensing performance of different positions of analyte placement is investigated. Through simulation analysis by different positions of analyte placement, it is revealed different RI detection. When the analyte is distributed across the entire outer ring region, the sensor exhibits the RI detection range from 1.2 to 1.34. The sensor achieves a maximum spectral sensitivity of 2000 nm/RIU and a resolution of 2 × 10⁻³ RIU. When the analyte is confined exclusively to the upper aperture, the sensor’s RI detection range extends from 1.33 to 1.46. The simulated results show that the proposed sensor achieves a maximum spectral sensitivity of 5600 nm/RIU and a resolution of 8 × 10⁻⁴ RIU. Regardless of which of the two positions the analyte is placed, the proposed D-shaped photonic crystal fiber (D-PCF) sensor has a broad operating wavelength. The excellent sensing performance makes the proposed SPR sensor a competitive candidate in RI detection applications.

Present report focuses on the design and optical perfect absorption/reflection properties of novel plasmonic metasurface made of square array of Si₃N₄ hemi-spheres on flat Si₃N₄ surface. The whole structure is sandwiched between flat gold layer and top gold coating. Theoretical study using Finite Difference Time Domain (FDTD) computation shows multiple near perfect absorptions (80–100%) with narrow line width (~ 50 nm) between 550 to 1500 nm. Four distinct absorption peaks (or reflection dips) are observed at 1020 nm (A1), 888 nm (A2), 614 nm (A3), 740 nm (A4) which can be manipulated by varying structural parameters such as period, hemi-sphere diameter and top gold coating thickness. These multiple absorptions arise due to electric dipolar resonance, magnetic resonance, excitation of various surface plasmon modes (such as (1,0); (2,0); (1,1)) and cavity mode, as evident from near-field analysis. With appropriate structural parameters, multiband well resolved near perfect absorptions are achieved at desired wavelengths. The proposed metasurface is insensitive to the polarization of excitation beam, and has relatively large launch angle tolerance (~ 20°), making it suitable for optical and optoelectronic device integration.