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The larger electric or magnetic Purcell factor demonstrates that the structure can be utilized as an electric or magneto-optical emission project. Their simultaneous realization offers the potential for integrated circuits to achieve selective photon sources. In this study, we put forth a proposal for the simultaneous attainment of substantial electrical and magnetic Purcell enhancements. In our hybrid metal–dielectric metasurface, the toroidal dipole (TD) quasi bound states in the continuum mode and the electric dipole (ED) mode are strongly coupled, so the hybrid mode combines the advantages of both, with a large Q factor and a small mode volume. The design implements a Rabi splitting energy of 222 meV between the TD quasi-BIC and ED modes, achieving an electric Purcell factor of 43 and a magnetic Purcell factor of 684, which are greater than those observed for the metal rod and dielectric structure, respectively. This paves the way for the development of high-performance hybrid optoelectronic applications. [ABSTRACT FROM AUTHOR]

We have investigated the modulation of the trapping potential and trapping force provided by the graphene charge transfer plasmon (CTP) structure that supports two resonance modes. Both the screened bonding dipolar plasmon mode and the charge transfer plasmon mode greatly provide a strong trapping potential and trapping force. The position of the trapping potential well can be dynamically regulated by modulating the Fermi energy or the geometry of the charge transfer bridge, allowing for the dynamic trapping of the nanoparticles. The restricted Brownian motion trajectory of the nanoparticles near the structure indicates that both modes can achieve stable nanoparticles trapping. These two peculiar resonance modes could potentially open up additional possibilities for optical manipulation and particle sorting. [ABSTRACT FROM AUTHOR]

We present a high-performance refractive index sensor based on Fano resonance with a figure of merit (FOM) about 56.5 in all-dielectric metasurface which consists of a periodically arranged silicon rings with two equal splits dividing them into pairs of arcs of different lengths. A Fano resonance with quality factor ~133 and spectral contrast ratio ~100% arises from destructive interference of two antiphase electric dipoles in the two arcs of the split-ring. We can turn on and/or off the Fano resonance with a modulation depth nearly 100% at the operating wavelength of 1067 nm by rotating the polarization of incident light. We believe that our results will open up avenues for the development of applications using Fano resonance with dynamically controllability such as biochemical sensors, optical switching, and modulator. [ABSTRACT FROM AUTHOR]

We present a multi-band terahertz absorber formed by periodic square metallic ribbon with T-shaped gap and a metallic ground plane separated by a dielectric layer. It is demonstrated that absorption spectra of the proposed structure consist of four absorption peaks located at 1.12, 2.49, 3.45, and 3.91 THz with high absorption coefficients of 98.0, 98.9, 98.7, and 99.6%, respectively. It is demonstrated that the proposed absorber has the tunability from single-band to broadband by changing the length of square metallic ribbon and we can also select or tune the frequencies which we want to use by changing polarization angles. Importantly, the quality factor Q at 3.91 THz is 30.1, which is 5.6 times higher than that of 1.12 THz. These results indicate that the proposed absorber has a promising potential for devices, such as detection, sensing, and imaging. [ABSTRACT FROM AUTHOR]

The study aimed to determine if the variability of the effect of boron (B) deficiency on Newhall navel orange grafted on trifoliate orange (deficient-B-sensitive) and on citrange (deficient-B-tolerant) can be explained on the basis of changes in cell-wall content and in cell-wall B and calcium (Ca) concentrations. The plants were cultured in the nutrient solution (with or without B) for 65 days. Boron deficiency increased the cell-wall content in old leaves (leaves from last season) of trifoliate orange but had no impact on citrange. Boron deficiency did not reduce B concentration in cell walls of old leaves of citrange-grafted plants but increased their Ca concentration. For trifoliate-orange-grafted plants, however, B deficiency decreased the B concentration in cell walls of old leaves and did not increase their Ca concentration. The changes of B and Ca concentrations between with and without B supply in pectin were in good agreement with the changes of those in cell walls. The relatively greater ability of citrange-grafted plants to maintain B and Ca in the cell wall may contribute to their tolerance to low external B. [ABSTRACT FROM AUTHOR]

Many applications involve the phenomenon of a material absorbing electromagnetic radiation. By exploiting wave interference, the efficiency of absorption can be significantly enhanced. Here, we propose Friedrich-Wintgen bound states in the continuum (F-W BICs) based on borophene metamaterials to realize coherent perfect absorption with a dual-band absorption peak in commercially important communication bands. Metamaterials consist of borophene gratings and a borophene sheet that can simultaneously support a Fabry-Perot plasmon resonance and a guided plasmon mode. The formation and dynamic modulation of the F-W BIC can be achieved by adjusting the width or carrier density of the borophene grating, while the strong coupling leads to the anti-crossover behavior of the absorption spectrum. Due to the weak angular dispersion originating from the intrinsic flat-band characteristic of the deep sub-wavelength periodic structure, the proposed plasmonic system exhibits almost no change in wavelength and absorption at large incident angles (within 70 degrees). In addition, we employ the temporal coupled-mode theory including near- and far-field coupling to obtain strong critical coupling, successfully achieve coherent perfect absorption, and can realize the absorption switch by changing the phase difference between the two coherent beams. Our findings can offer theoretical support for absorber design and all-optical tuning.

We propose a two-dimensional array made of a double-layer of vertically separated graphene nanoribbons. The transfer matrix method and coupled mode theory are utilized to quantitatively depict the transfer properties of the system. We present a way to calculate the radiative and the intrinsic loss factors, combined with finite-difference time-domain simulation, conducting the complete analytical analysis of the unidirectional reflectionless phenomenon. By adjusting the Fermi energy and the vertical distance between two graphene nanoribbons, the plasmonic resonances are successfully excited, and the unique phenomena can be realized at the exceptional points. Our research presents the potential in the field of optics and innovative technologies to create advanced optical devices that operate in the mid-infrared range, such as terahertz antennas and reflectors.

We have investigated the effect of enhanced optical force via the acoustic graphene plasmon (AGP) cavities with the ultra-small mode volumes. The AGP mode can generate stronger field confinement and higher momentum, which could provide giant optical force, and has no polarization preference for the optical source. We have demonstrated that the trapping potential and force applied on polystyrene nanoparticle in the AGP cavities are as high as -13.6 × 10 2 k B T/mW and 2.5 nN/mW, respectively. The effect of radius of rounded corners and gap distance of AGP cavities on the optical force has been studied. Compared with an ideal nanocube, nanocube with rounded corners is more in line with the actual situation of the device. These results show that the larger radius of nanocube rounded corners, the smaller trapping potential and force provided by AGP cavities. Our results pave a new idea for the investigation of optical field and optical force via acoustic plasmon mode.

Diabetes mellitus is one kind of chronic diseases which seriously threaten human health. It is very important to diagnose in the early stage. With the development of diabetes, the structure and function of erythrocyte in the blood will change. So the peak position and peak height of erythrocyte fluorescence spectrum are different. These differences can be used to determine the status of diabetes. In the selection of the difference of spectral signal as the feature vector, the nonlinear degree of fluorescence spectrum can be used as the feature vector. In order to describe the nonlinearity of the fluorescence spectrum signal, the nonlinear degree of the signal is described with the delay vector variance (DVV) method. By using the method of iterative amplitude adjusted Fourier transformation (IAAFT) to generate surrogate data of raw data, the nonlinear characteristic of the raw data is determined by comparing the DVV of the original data and the surrogate data. The variance of the original data is the horizontal coordinates, and the variance of the surrogate data is the longitudinal coordinates, thus the DVV scatter plot is drawn. The DVV scatter plot of healthy rat erythrocyte fluorescence spectrum is almost coincident with its diagonal, which means the nonlinear degree of healthy rat erythrocyte fluorescence spectrum is lower. The DVV scatter plot of diabetic rat erythrocyte fluorescence spectrum deviates from its diagonal, which means the nonlinear degree of healthy rat erythrocyte fluorescence spectrum is higher, also the corresponding amino acid spectrum nonlinearity is deeper. Therefore, it is proposed that the nonlinear difference between the healthy and diabetic fluorescence spectrum can be used as a feature of early diabetes diagnosis.

By using confocal Raman spectroscopy, Raman spectra were measured in normal rat red blood cells, normal human red blood cells, STZ induced diabetetic rats red blood cells, Alloxan induced diabetetic rats red blood cells and human type 2 diabetes red blood cells. Then principal component analysis (PCA) with support vector machine (SVM) classifier was used for data analysis, and then the distance between classes was used to judge the degree of close to two kinds of rat model with type 2 diabetes. The results found significant differences in the Raman spectra of red blood cell in diabetic and normal red blood cells. To diabetic red blood cells, the peak in the amide VI C=O deformation vibration band is obvious, and amide V N-H deformation vibration band spectral lines appear deviation. Belong to phospholipid fatty acyl C-C skeleton, the 1 130 cm(-1) spectral line is enhanced and the 1 088 cm(-1) spectral line is abated, which show diabetes red cell membrane permeability increased. Raman spectra of PCA combined with SVM can well separate 5 types of red blood cells. Classifier test results show that the classification accuracy is up to 100%. Through the class distance between the two induced method and human type 2 diabetes, it is found that STZ induced model is more close to human type 2 diabetes. In conclusion, Raman spectroscopy can be used for diagnosis of diabetes and rats STZ induced diabetes method is closer to human type 2 diabetes.