Vanadium dioxide (VO2) is a temperature phase change material that has metallic properties at high temperatures and insulation room temperature. In this article, novel device been designed based on the dielectric metasurface consisting of VO2 graphene array, which can achieve multiple functions by adjusting voltage. When (340 K), in absorption state its absorptivity be dynamically controlled changing On other hand, polarization under temperature, electromagnetic waves voltage graphene. This...

Optical metasurfaces exhibit unprecedented ability in light field control due to their locally change the phase, amplitude, and polarization of transmitted or reflected light. We propose a multifunctional metalens with dual working modes based on bilayer geometric phase elements consisting low-loss materials (Sb 2 Se 3 ) amorphous silicon (a-Si). In transmission mode, by changing crystalline state Sb scatterer, bifocal an arbitrary intensity ratio at telecommunication C-band is realized,...

A dispersion hybrid implicit-explicit-finite-difference time-domain (HIE-FDTD) method is used to simulate a graphene-based polarizer in this paper. The surface conductivity of graphene incorporated into the conventional HIE-FDTD directly through an auxiliary difference equation (ADE). time step size proposed has no relation with fine spatial cells layer. simulation results show that calculated result agrees very well ADE-FDTD method, but its computational considerably reduced. By using it...

A dispersion hybrid implicit–explicit finite‐difference time‐domain (HIE‐FDTD) method is proposed for simulating the graphene‐based absorber at terahertz frequencies. The surface conductivity of graphene derived from Kubo formula incorporated into conventional HIE‐FDTD algorithm by using auxiliary differential equation technique. time step size this not related with fine cells inside layer. simulation result infinite sheet shows that has high computational accuracy and greatly reduced...

Recently graphene has attracted tremendous attention for its excellent properties. Numerous novel graphene-based devices have come out, showing great potential of applications at the terahertz band. In this paper, by placing monolayer deposited on top a SiO2/Si substrate, tunable dipole antenna owing to voltage-controllable conductivity is obtained. The resonance frequency proposed blue-shift with increasing chemical potential. Furthermore, radiation gain can increase from 3.7dBi 5.5dBi...

The effect of hydrostatic pressure (up to 28 MPa) on Brillouin frequency shift (BFS) within two types bare, single-mode fibers is studied via optical time domain analysis technique.Experimental results show a negative linear relation between and BFS, with almost the same sensitivity in both fibers.The average value experimental slopes -0.742MHz/MPa.This found be well suited theoretical basis data bulk silica glass previous reports.This preliminary evaluation may result new method for...

Compared with one-way wave equation migration and ray-based migration, reverse time (RTM) using two-way propagation information can produce accurate imaging results for complex structures. Its computational accuracy efficiency are mainly determined by numerical methods wavefield simulation. When traditional regular grids seismic modeling, scattering artifacts may occur due to the stepped approximation of layer interfaces rugged topography. On other hand, irregular require a grid generation...

Without zero-crossings, dc series arc faults result in much more serious safety threats. As the voltage level rises and system capacity increases, appear systems frequently. To eliminate their damages, specific fault circuit interrupters (AFCI) should be developed. In this paper, two kinds of are considered designed experimental setup. Firstly, a simulated source with ac-dc-dc structure is connected to resistor. This could act as constant or photovoltaic (PV) by operating different U-I...

A dispersive weakly conditionally stable finite-difference time-domain (WCS-FDTD) method for the efficient simulations of graphene-based absorbers with fine structures in two directions is proposed this paper. It based on auxiliary differential equation technique and hybrid implicit explicit difference technique. The maximum time step size only determined by largest spatial discretization. numerical results demonstrate that WCS-FDTD has high computational accuracy greatly reduced compared...

Abstract This paper derives exactly the stability condition of dispersive hybrid implicit‐explicit finite‐difference time‐domain (HIE‐FDTD) method used for simulations graphene‐based devices. Combining with Routh‐Hurwitz criterion, an analytical closed‐form expression is obtained. The result shows that maximum time increment HIE‐FDTD only associated two spatial discretizations instead smallest one inside graphene layer. Numerical example validates this condition.

Frequency-domain finite-difference (FDFD) modeling plays an important role in exploration seismology. However, a major disadvantage of FDFD is the computational cost, especially for large-scale models. By compactly distributing nonzero strips, elongated stencil helps to generate narrow-bandwidth impedance matrix, improving efficiency without sacrificing numerical accuracy. To further improve accuracy and modeling, we have developed optimal method with 2D acoustic-wave modeling. The Laplacian...

Vertical comb drives are critical for electrostatic optical switches and variable attenuators (VOAs), but fabricating vertical comb-drives suffers from the difficulty of dealing with comb-finger misalignment. This paper presents a drive design its micro-fabrication method that can realize self-aligned two-level fingers. The fingers enabled by novel vertically-elevated flat-end (VEFE) bimorph structure. Both stator rotor -drive formed same photomask silicon etching step, which automatically...

Aperture averaging effect can smooth the optical signal fluctuations. Generally, aperture function is assumed to be a single circle when its K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> calculated. In recent years, of complex receiving also discussed. Actually, Cassegrain system usually used as telescope for free-space communication. There little bit difference from previous analysis analyze effect. analyzed in this paper. The...

Recently graphene has attracted tremendous attention for its excellent properties Numerous novel graphene-based devices have come out, showing great potential of tunable applications at THz band In this paper, by stacking a monolayer on the top polymer substrate, absorber is obtained owning to voltage-controllable conductivity graphene. Furthermore, absorption spectra different chemical potentials discussed in detail. The resonance frequency blue-shift with increasing potential. addition,...

The temperature compensation method of BOTDR strain monitoring system is proposed, which based on Raman Optical Time Domain Reflectometer (ROTDR), aiming at coupling effects Brillouin (BOTDR) technology. Then the effectiveness this proved theoretical and experimental studies, provides an effective means improving accuracy monitoring.

The magnetically biased graphene has the polarization rotation characteristics which is useful to design polarizer. But this characteristic difficult simulate by using finite-difference time-domain (FDTD) method, not only due graphene's thin layer confines time step size, but also because of isotropic surface conductivity when it static magnetic field. To solve problem, study presents an anisotropic hybrid implicit-explicit FDTD method. This method uses auxiliary difference equations...

Research in the field of laser atmospheric propagation has been continued for many years. Due to turbulence, actual systems are facing a lot technical problems. It leads difficulty large-scale civilian use communication. In this paper, parameters transmission experiment analyzed. The study is usually based on first-order Rytov approximation. we analyze optical both and second-order

Single-positive multi-label learning (SPMLL) is a typical weakly supervised problem, where each training example annotated with only one positive label. Existing SPMLL methods typically assign pseudo-labels to unannotated labels the assumption that prior probabilities of all classes are identical. However, class-prior category may differ significantly in real-world scenarios, which makes predictive model not perform as well expected due unrealistic on application. To alleviate this issue,...

The hybrid implicit-explicit finite-difference time domain (HIE-FDTD) method is presented to simulate the graphene layer. By using auxiliary differential equation (ADE) and Pade fitting method, both interband intraband conductivity of are incorporated into HIE-FDTD method. step increment in proposed not determined by fine meshes layer, so computational efficiency this greatly improved from that conventional (FDTD) which well validated numerical examples. Besides, simulation also shows has...

A dispersive weakly conditionally stable finite-difference time-domain (WCS-FDTD) method is presented in this paper for the efficient simulations of graphene with fine structures two directions. The maximum time step size proposed only related largest spatial discretization, so it very suitable graphene-based devices numerical results demonstrate that WCS-FDTD has high computational accuracy and much than HIE-FDTD FDTD method.