Abstract Chirality is a universal geometric property in both micro‐ and macroworlds. Recently, optical chiral effects have drawn increased attention due to their great potential fundamental studies practical applications. Significantly, the response of artificial structures can be enhanced by orders magnitude compared that naturally occurring counterparts. These man‐made generally exhibit two types chirality: extrinsic chirality intrinsic chirality. The former relies on external illumination...

The polarization singularity in momentum space has recently been discovered as a new class of topological signatures Bloch modes photonic crystal slabs concerning the far-field radiations, beyond its near-field description with widely explored band theory. Bound states continuum (BICs) are demonstrated vortex eigenpolarization singularities and circular points (C points) also obtained based on BICs, opening up more possibilities for exotic light scattering various phenomena singular optics....

Abstract The poor electronic conductivity of conversion‐type materials (CMs) and the dissolution/diffusion loss transition metal (TM) ions in electrodes seriously hinder practical applications potassium ion batteries. Simply optimizing electrode or designing components is no longer effective improving performance CMs. Binders, as one components, play a vital role electrochemical Here we rationally designed FeF 2 for first time by with introduction carbon nanotubes (CNTs) combined sodium...

A metamaterial (MM) differs from an ordinary optical material mainly in that it has a dispersive magnetic permeability and offers greatly enhanced design freedom to alter the linear nonlinear properties. This makes possible for us control propagation of ultrashort electromagnetic pulses at will. Here we report on generic features pulse demonstrate controllability both parameters models MMs. First, derive generalized system coupled three-dimensional Schr\"odinger equations (NLSEs) suitable...

We establish a general propagation model to describe the spin Hall effect of light beam in left-handed materials (LHMs). A spin-dependent shift centroid perpendicular refractive index gradient for through an air-LHM interface is demonstrated. For certain circularly polarized component, whether transverse positive or negative depends on magnitude gradient. Very surprisingly, LHM unreversed, although sign reversed. The physics underlying this counterintuitive that angular momentum photons...

We show that modulation instability may occur even in the normal group-velocity dispersion regime, or case of no metamaterials with a nonlinear electric polarization. The physical origin is additional second-order effect resulted from combination linear dispersive magnetic permeability Based on Drude model, numerical simulation performed to confirm theoretical predictions, and detailed discussion role both negative-index positive-index regions metamaterial presented.

Highly sensitive and low-cost surface-enhanced Raman scattering (SERS) substrates are essential for practical applications of SERS. In this work, we report an extremely simple but effective approach to achieve SERS detection molecules (down 10–10 M) by using a particle/molecule/film sandwich configuration. Compared conventional which preprepared absorb analyte detection, the proposed configuration is achieved postassembling flexible transparent gel tape embedded with plasmonic nanoparticles...

The intrinsic chirality of natural materials is usually weak or absent. To enlarge circular dichroism, chiral metasurfaces supporting bound states in the continuum have been widely investigated. These demonstrated considerable potential to achieve high quality (Q) factors but require ultra-small structure asymmetry and complicated fabrication processes. Here we propose a novel approach break in-plane symmetry by introducing refractive index perturbations. Furthermore, demonstrate efficient...

Fishnet metamaterials have shown their excellent absorption at terahertz and optical frequencies. Here, we experimentally demonstrate an ultra-broadband lightweight microwave absorber by fabricating a conventional magnetic absorbing material into fishnet-like structure. Compared with the pure material, broadest bandwidth (less than −10 dB) of is extended from 7.4–11 GHz to 4.8–20.7 GHz. Meanwhile, high surface density, which important shortcoming for materials, has been reduced clearly...

Composite microspheres with carbonyl iron cores and graphite shells are prepared by a mechanical ball milling method. The microwave absorption properties of these investigated in terms complex permittivity permeability, impedance matching property, reflection loss. morphology conductivity the can be well tuned controlling time to achieve improvement its characteristics. In addition, integration composition unique structure, iron/graphite possess better than graphite. show highly strong...

MoS2 is a promising material with microwave absorption performance due to its high dielectric properties and low density. However, pure non-magnetic has bad impedance matching characteristic. In this study we prepared the Ni/MoS2 nanocomposites by cladding micrometer slices magnetic Ni nanoparticles. Our results show that of have been improved obviously compared MoS2. Because introduction particles, permeability turned from one complex, indicating newly added loss. Meanwhile, big gap between...

Seeking for ultrasensitive and low-cost substrates is highly demandable practical applications of surface-enhanced Raman scattering (SERS) technology. In this work, we report an SERS-active substrate based on wet-chemistry-synthesized vertically aligned large-area TiO2 nanosheets (NSs) decorated by densely packed gold nanoparticles (Au NPs) with sub-5 nm gaps. Via a multistep successive deposition process, three-dimensional-stacked Au NPs sandwiched 3 SiO2 layer were assembled onto the NS,...

We proposed and demonstrated a scheme to enhance tune absorption properties of conventional microwave absorbing materials (MAMs) by metamaterials (MMs). By covering MAM, say, carbonyl iron powder coating, with MMs composed split ring resonators (SRRs) wires, we show both experiments simulations that the maximum reflection loss (RL) is increased significantly frequency region for shifted lower frequency. The in which RL less than −10 dB shifts from 5–7 4.2–6.2 GHz perpendicular polarization...

The absorption of conventional metamaterial absorbers (MMAs), originating from the electric or magnetic resonance induced ohmic loss, usually has a narrow bandwidth because limited surface resistance structured metal layers. In this letter, we experimentally demonstrate broadband MMA by using graphite instead copper to construct pattern structure. Compared with metals, low conductivity, and its skin depth is far more than those metals. As result, effective thickness our graphite-based...

We propose a scheme to controllably convert the wave front of an arbitrary incident beam into helical one by compact transformation slabs, thus enabling output carry desirable orbital angular momentum (OAM). First, based on optics, three-dimensional (3D) phase between any two fronts flat media is established and then used mold Gaussian one. Second, 3D finite-difference time-domain simulations are performed confirm spiraling evolutions resultant field phase, clearly demonstrating OAM...

We explain the rotational Doppler effect associated with light beams carrying orbital angular momentum in left-handed materials (LHMs). demonstrate that LHMs is unreversed, which significantly different from axial effect. The physics underlying this intriguing combined contributions of negative phase velocity and inverse screw wave front. find additional caused by Gouy wave-front curvature should be reversed, because index. In normal dispersion region, induces an upstream energy flow but a...

Core–shell structured Fe/C have been successfully derived from a metal-organic framework for microwave absorbing. Based on the measured electromagnetic parameters, it is found that maximum reflection loss (RL) of reaches [Formula: see text][Formula: text]dB at 5.8[Formula: text]GHz with thickness 3.0[Formula: text]mm and broadest absorption bandwidth ([Formula: text]dB) up to 6.0[Formula: (from 11.2 17.2[Formula: text]GHz) 1.5 mm. The excellent mainly ascribed multiple reflections, good...

A novel Fe/nanoporous carbon (Fe/NPC) composite was synthesized via Fe 3 O 4 nanoparticles coating in metal–organic framework. The pyrolysis conditions are carefully optimized, and the effects of temperature on electromagnetic parameters have been systematically analyzed. Among these candidates, Fe/NPC pyrolyzed at 800 °C (Fe/NPC‐800) shows eminent microwave absorption due to interface polarization well matched characteristic impedance. results indicate that effective reflection loss...