Plasmonics最新文献

In this study, an efficient bi-directional optical coupler has been proposed. Our approach involves the development of a novel mechanism aimed at coupling a plasmonic waveguide to a photonic crystal waveguide. The innovative design of the small-scale plasmonic-photonic crystal-plasmonic coupler (PW-PC-PW) facilitates optimal power transmission between these interconnected waveguides. To conduct comprehensive simulations of the plasmonic-photonic crystal-plasmonic waveguides, we employ the finite difference time domain (FDTD) method. By establishing a coupling between the photonic crystal and plasmonic structures, we achieve efficient signal transfer, thereby laying the foundation for the creation of diverse devices that amalgamate the advantages offered by plasmonic devices and photonic crystals. Consequently, the device outlined in this paper holds substantial promise as a pivotal component for various types of optical integrated circuit devices. The electromagnetic waves operating within this structure fall within the wavelength range of 1500 to 2050 nm, and the achieved transmittance value at a wavelength of λ = 1550 nm reaches an impressive 95%.

In this paper, a four-way filtering power divider (FPD) based on hybrid spoof surface plasmon polariton (SSPP) and substrate integrated waveguide (SIW) is designed and fabricated. It is for the first time that a four-way FPD has been implemented by integrating SIW and SSPP structures. This combination can guarantee a wide bandwidth which would not be attainable by employing merely SIW or SSPP. The presented hybrid structure has been realized by etching some butterfly grooves on the upper metal surface of SIW and half-mode SIW. The lower and upper cutoff frequencies of this hybrid SIW-SSPP FPD can be adjusted independently by tuning the dimensions of SIW and SSPP unites, respectively. Employing butterfly-shaped SSPPs instead of typical rectangular SSPPs with the same length leads to a reduction in the circuit’s size, higher slow-wave effects, and shorter wavelength. To validate the proposed design procedure, the presented FPD is fabricated and measured. A good agreement between the simulated and measured results is achieved. What stands out from the measured results is that the proposed circuit achieves a 3-dB fractional bandwidth of 38% from 4.2 to 6.2 GHz, a return loss of higher than 13.5 dB, and a minimum insertion loss of 0.7 dB.

The present study is centered around investigating the thermo-optical features and the performance concerning the inflection points (IFs) in hybrid composite nanostructures, focusing on Au- and Ag-decorated alloy configurations, and their response in diverse refractive index (RI) conditions (n = 1.30 to 1.55). Au-decorated alloys demonstrate intriguing localized plasmonic resonance (LSPR) exhibiting LSPR shifts in response to various RI’s, indicating improved response with notable red and blue shifts (({lambda }_{max}=) 502–564 nm) indicating effective absorption efficiency. In contrast, Ag-decorated alloys exhibit enhanced absorption efficiency at higher RI’s, presenting minimal LPSR shifts (({lambda }_{max}=) 398–449 nm) among various RI’s. In the context of thermoplasmonics, the surface temperature of Au/Ag-decorated nanocomposites exhibits ranges of 2.39 to 3.03 (^circ{rm C}), and 2.09 to 3.55 (^circ{rm C}) for specific optical flux, respectively. Furthermore, an improvement in RI sensitivity is achieved, ranging from 144 to 308 nm/RIU for Au-decorated and 164 to 180 nm/RIU for Ag-decorated alloy nanocomposites. Detailed scrutiny of Au and Ag-layered alloy nanostructures suggests new opportunities towards ultra-sensitive biosensors and precise biomedical uses.

Graphical Abstract

This work presents a theoretical approach to the coherent manipulation of wavelength interrogation of sensitivity of the surface plasmon polariton waves (SPPs) at silver metal and dielectric interface using grating geometry. The wavelength interrogation of sensitivity of SPPs with respect to refractive index is given as (dlambda /dn_d). Significant control in sensitivity is reported with probe and control fields detuning and Rabi frequency as well as decay rates. The order of diffraction and grating period plays an important role in the manipulation of sensitivity. The sensitivity increases with increasing grating period and decreases with increasing order of diffraction. The sensitivity is the oscillation function of probe field detuning and Rabi frequency. A maximum value of sensitivity is reported to have 800 nm/RIU with probe field detuning and Rabi frequency. The investigated results are useful in biological and optical technology.

In this manuscript, numerical investigations at the chiroplasma-metal planar interface have been performed to explore some features of surface plasmon polaritons (SPPs). Based on the electromagnetic wave theory, we derive a dispersion relation. The effect of tensorial permittivity parameters on effective mode index and propagation loss is analyzed in detail. Numerical results show that chiroplasma parameters, i.e., chirality, cyclotron frequency, and plasma frequency, have a significant impact on effective mode index and propagation loss in the THz frequency spectrum. The presented results of chiroplasma-metal SPPs provide new possibilities to fabricate compact nanophotonic devices in the THz frequency regime.

The objective of this study was to prepare metallic gold nanoparticles (AuNPs) from the Diospyros kaki L. (persimmon) leaf (DKL) extract, which was grown in the Trabzon province of Türkiye, using microwave extraction. Separate additions of 0.1 and 0.5 mL DKL extract were made to the 0.5 mM HAuCl₄.3H₂O solution while the heater was kept at 25 °C and stirring continuously. In this method, UV-Vis spectroscopy (300–800 nm) absorption measurements were performed on extracts of Diospyros kaki L. leaves at different time intervals (10, 20, 30, 60, 120, and 1440 min). Green chemistry principles were utilized in the preparation of gold nanoparticles (AuNPs), which were characterized by UV–visible, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and Zetasizer. FTIR analysis can be used to determine the various functional groups that were synthesized in the gold (Au) nanoparticles. Based on the AuNPs’ XRD peaks, the average crystallite size was determined to be 25.99 nm. Zetasizer study results showed that the average particle size of Au nanoparticles produced by microwave extraction in an aqueous medium was 45.44 ± 1.095 nm, the zeta potential (ZP) was − 16.9 mV ± 1.19, and the polydispersity index was 0.316 ± 0.009. The UV-Vis absorption spectra of the AuNP solutions were stable for approximately 2.5 to 3 months when they were kept in a refrigerator.

The development of Liquid crystals (LCs) based technology is happening at a quick pace to design various switchable optical devices due to the exceptional electro-optical properties of LCs. The purity of an LC is the primary concern for these applications. Here, we propose a straightforward and effective optical method to detect the purity of an LC using surface plasmon resonance phenomena. The Kretschmann configuration is used in the proposed technique, and an LC cavity is formed over the metal layer using a glass substrate. Various impurities are added in the pure LC, which disturbs the molecular arrangement of the LC molecules, and hence, the refractive index of LC changes. We have numerically calculated and experimentally observed the shift in the resonance angle for the impure LC as compared to the pure one. The impurity in the LC is evident from the significant shift in the resonance angle. The experimentally measured sensitivity of the proposed technique is around 150⁰/RIU, which is comparable to the other Kretschmann configuration-based sensors. This sensitivity is suitable for LC material, especially for their uses in optics and photonics applications. In comparison to the existing LC purity detection method, the key advantages of the proposed method are its lightweight, compact design, label-free detection, and real-time monitoring capabilities.

The study on temperature sensors based on surface plasmon resonance (SPR) sensors has received less attention than the widespread use of temperature sensors in daily life and industry. As a result, this article proposes an SPR temperature sensor with a structure consisting of gold (Au) film and liquid crystal (LC) film. The application of SPR phenomena in liquid crystals (LCs) for temperature monitoring is investigated in this work. The resonance angle is analyzed in this experiment to detect temperature differences between 15 and 85 °C. The findings show that temperature variations cause appreciable fluctuations in the SPR temperature sensor’s values, exposing the sensitivity of various LC kinds. The simulations revealed slight differences in the resonance angles of TL-216, MLC-9200-000, MLC-6608, E44, and MLC-9200-100 among the LCs under study, which presents a problem for their application as accurate temperature sensors. But when 633 nm and 656 nm wavelengths were considered, the E7 LC showed promise as an efficient temperature sensor within the given temperature range. The study found that the LCs had different sensitivities; the highest sensitivity was measured at 0.249 deg/°C and the lowest at 0.002 deg/°C. The results highlight the potential of SPR-based LCs, particularly E7, as trustworthy temperature sensors within the given temperature ranges, providing information about their possible use in temperature-sensitive settings.

A highly sensitive surface plasmon resonance biosensor employing BK7 prism, Silver (Ag), zinc oxide (ZnO), ferromagnetic material (Fe₂O₃), and two-dimensional (2D) nanomaterial black phosphorous (BP) has been proposed. Thin layers of two different oxide layers sandwiched between Ag and BP in Kretschmann configuration. The angular interrogation method–based numerical simulation is applied for modelling of high performance SPR biosensor at a wavelength of 633 nm (visible region). Transfer matrix method and finite element methods have been used to obtain [performance parameters. This sensor can detect malaria at different stages and provides a large range of refractive index (RI) sensing from 1.369 to 1.409. The RI for malaria stages, including the ring, trophozoite, and schizont stages, are 1.396, 1.381, and 1.371 respectively, with corresponding angular sensitivities of 367 deg/RIU, 297 deg/RIU, and 269 deg/RIU. The sensor offers an ultrahigh angular sensitivity for malaria detection in ring stage. This research could pave the way for an important bio sample detection apparatus that allows for quick and precise in ring stage diagnosis.