Chuwen Lan

Isotropic Mie resonance-based metamaterial perfect absorber

An isotropic Mie resonance-based metamaterial perfect absorber with near unity absorbance is experimentally and numerically demonstrated. The metamaterial is constructed with an array of dielectric cubes and a metallic ground plane. The absorption peak of the metamaterial perfect absorber is dependent on the permittivity and the side length of the dielectric cubes. A good agreement between experimental and simulated result at X band absorption is achieved.

Magnetically coupled electromagnetically induced transparency analogy of dielectric metamaterial

In this manuscript, we experimentally demonstrate magnetically coupled electromagnetically induced transparency (EIT) analogy effect inside dielectric metamaterial. In contrast to previous studies employed different metallic topological microstructures to introduce dissipation loss change, barium strontium titanate, and calcium titanate (CaTiO3) are chosen as the bright and dark EIT resonators, respectively, due to their different intrinsic dielectric loss. Under incident magnetic field excitation, dielectric metamaterial exhibits an EIT-type transparency window around 8.9 GHz, which is accompanied by abrupt change of transmission phase. Numerical calculations show good agreement with experiment spectra and reveal remarkably increased group index, indicating potential application in slow light.

Tunable dual-band negative refractive index in ferrite-based metamaterials

A tunable dual-band ferrite-based metamaterial has been investigated by experiments and simulations. The negative permeability is realized around the ferromagnetic resonance (FMR) frequency which can be influenced by the dimension of the ferrites. Due to having two negative permeability frequency regions around the two FMR frequencies, the metamaterials consisting of metallic wires and ferrite rods with different sizes possess two passbands in the transmission spectra. The microwave transmission properties of the ferrite-based metamaterials can be not only tuned by the applied magnetic field, but also adjusted by the dimension of the ferrite rods. A good agreement between experimental and simulated results is demonstrated, which confirms that the tunable dual-band ferrite-based metamaterials can be used for cloaks, antennas and absorbers.

Dual band metamaterial perfect absorber based on artificial dielectric "molecules"

Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric “molecules” with high symmetry. The artificial dielectric “molecule” consists of four “atoms” of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence.

Negative and near zero refraction metamaterials based on permanent magnetic ferrites

Ferrite metamaterials based on the negative permeability of ferromagnetic resonance in ferrites are of great interest. However, such metamaterials face a limitation that the ferromagnetic resonance can only take place while an external magnetic field applied. Here, we demonstrate a metamaterial based on permanent magnetic ferrite which exhibits not only negative refraction but also near zero refraction without applied magnetic field. The wedge-shaped and slab-shaped structures of permanent magnetic ferrite-based metamaterials were prepared and the refraction properties were measured in a near-field scanning system. The negative and near zero refractive behaviors are confirmed by the measured spatial electric field maps. This work offers new opportunities for the development of ferrite-based metamaterials.

Simultaneously concentrated electric and thermal fields using fan-shaped structure

In recent years, considerable attention has been focused on transformation optics and metamaterial due to their fascinating properties and wide range of promising applications. Concentrator, one of the most well-known applications of transformation optics and metamaterial, is now limited only to a single physical domain. Here we propose and give the experimental demonstration of a bifunctional concentrator that can concentrate both electric and thermal fields to a given region simultaneously while keeping the external fields undistorted. Fan-shaped structure composed of alternating wedges made of two kinds of natural materials is proposed to achieve this goal. Numerical simulation and experimental results show good agreement, indicating the soundness and feasibility of our scheme.

Electrostatic Field Invisibility Cloak.

The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect has been achieved via both cancelling technology and transformation optics (TO). This study demonstrates a novel way for manipulating electrostatic fields, which shows promise for a wide range of potential applications.

Tailorable Zero‐Phase Delay of Subwavelength Particles toward Miniaturized Wave Manipulation Devices

Adjustable zero-phase delay and equiphase control are demonstrated in single and multilayer dielectric particle arrays with high index and low loss. The polarization-independent near-zero permeability is the origin of the wave control near the first Mie magnetic resonance. The proposed design paves the way for subwavelength devices and opens up new avenues for the miniaturization and integration of THz and optical components.

Dual band metamaterial perfect absorber based on Mie resonances

We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric “atom” with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric “atom” and copper plate. Mie resonances of dielectric “atom” provide a simple way to design metamaterial perfect absorbers with high symmetry.

Hyperbolic metamaterial based on anisotropic Mie-type resonance

A hyperbolic metamaterial (MM) based on anisotropic Mie-type resonance is theoretically and experimentally demonstrated in microwave range. Based on the shape-dependent Mie-type resonance, metamaterials with indefinite permeability or permittivity parameters are designed by tailoring the isotropic particle into an anisotropic one. The flat lens consisting of anisotropic dielectric resonators has been designed, fabricated and tested. The experimental observation of refocusing and a plane wave with ominidirectional radiation directly verify the predicted properties, which confirm the potential application in negative index material and superlens. This work will also help to develop all-dielectric anisotropic MM devices such as 3D spatial power combination, cloak, and electromagnetic wave converter, etc.