Hai-Ming Li

Low-loss metamaterial electromagnetically induced transparency based on electric toroidal dipolar response

In this paper, a low-loss and high transmission analogy of electromagnetically induced transparency based on electric toroidal dipolar response is numerically and experimentally demonstrated. It is obtained by the excitation of the low-loss electric toroidal dipolar response, which confines the magnetic field inside a dielectric substrate with toroidal geometry. The metamaterial electromagnetically induced transparency (EIT) structure is composed of the cut wire and asymmetric split-ring resonators. The transmission level is as high as 0.88, and the radiation loss is greatly suppressed, which can be proved by the surface currents distributions, the magnetic field distributions, and the imaginary parts of the effective permeability and permittivity. It offers an effective way to produce low-loss and high transmission metamaterial EIT.

Complete photonic band gaps and tunable self-collimation in the two-dimensional plasma photonic crystals with a new structure

In this paper, the properties of complete photonic band gaps (CPBGs) and tunable self-collimation in two-dimensional plasma photonic crystals (2D PPCs) with a new structure in square lattices, whose dielectric fillers (GaAs) are inserted into homogeneous and nomagnetized plasma background are theoretically investigated by a modified plane wave expansion (PWE) method with a novel technique. The novel PWE method can be utilized to compute the dispersion curves of 2D PPCs with arbitrary-shaped cross section in any lattices. As a comparison, CPBGs of PPCs for four different configurations are numerically calculated. The computed results show that the proposed design has the advantages of achieving the larger CPBGs compared to the other three configurations. The influences of geometric parameters of filled unit cell and plasma frequency on the properties of CPBGs are studied in detail. The calculated results demonstrate that CPBGs of the proposed 2D PPCs can be easily engineered by changing those parameters, and the larger CPBGs also can be obtained by optimization. The self-collimation in such 2D PPCs also is discussed in theory under TM wave. The theoretical simulations reveal that the self-collimation phenomena can be found in the TM bands, and both the frequency range of self-collimation and the equifrequency surface contours can be tuned by the parameters as mentioned above. It means that the frequency range and direction of electromagnetic wave can be manipulated by designing, as it propagates in the proposed PPCs without diffraction. Those results can hold promise for designing the tunable applications based on the proposed PPCs.

Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

Electromagnetically induced transparency with large group index induced by simultaneously exciting the electric and the magnetic resonance

In this paper, we numerically and experimentally demonstrate classical analogy of electromagnetically induced transparency (EIT) with simultaneously exciting the electric and the magnetic resonance. The cut wire and the split-ring resonator (SRR) are chosen as the bright and the quasi-dark EIT resonators, respectively. Under incident electromagnetic wave illumination, an EIT-like sharp transmission window can be observed. The group index exceeds 140, which can be applied for slow electromagnetic wave velocity. Furthermore, the underlying physics can be interpreted by the concept of hybridization model. The simultaneous excitation of the electric and the magnetic resonance can make up for the shortcomings of the other existing designs. More importantly, it can enrich metamaterial analogy of electromagnetically induced transparency.

Evanescent wave decomposition in a novel resonator comprising unmagnetized and magnetized plasma layers

A 4 × 4 transfer matrix method has been applied to study the decomposition of any elliptically polarized wave in a magnetized resonator. When the incident elliptically polarized wave passes through the structure, it is orthogonally decomposed into two circular polarizations at two resonance frequencies. Without changing the structure of the resonator, the positions of the resonant frequencies of the right- and left-handed circularly polarized waves can be modulated by changing the external magnetized field. The results show that the proposed magnetized structure can be used to design a novel resonator, which can be applied in the decomposition of polarized electromagnetic waves.

Tailoring electromagnetically induced transparency with different coupling mechanisms.

Tailoring electromagnetically induced transparency with two different coupling mechanisms has been numerically demonstrated. The results show that EIT based on simultaneous electric resonance and magnetic resonance has relatively larger coupling distance compared with that based on electric resonance near field coupling to magnetic resonance. The relatively large coupling distance is due to the relatively small susceptibility change. For EIT based on simultaneous electric resonance and magnetic resonance, not only incident electric field but also the incident magnetic field pays a role on the susceptibility of system. The influence of the incident magnetic field leads to relatively smaller susceptibility change compared with that based on electric resonance near field coupling to magnetic resonance.

A comparative study of band Faraday effects in 3D magnetized photonic crystals with different high-symmetry lattices with uniaxial materials

In this paper, the band Faraday effects in three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) composed of anisotropic dielectric (the uniaxial material) spheres immersed in uniform magnetized plasma background with various lattices including the face-centered-cubic (fcc), body-centered-cubic (bcc), and simple-cubic (sc) lattices are theoretically investigated by a modified plane wave expansion (PWE) method, as the Faraday effects of magnetized plasma are considered (the incidence electromagnetic wave vector is parallel to the external magnetic field at any time). The equations for calculating the anisotropic PBGs in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and a flatbands region can be achieved as the uniaxial material introduced into 3D MPPCs. The 3D MPPCs with fcc, bcc, sc lattices will not exhibit a complete PBG unless the uniaxial material is introduced. The influences of the ordinary refractive index, extraordinary refractive index, filling factor, plasma frequency, and plasma cyclotron frequency (the external magnetic field) on the properties of anisotropic PBGs for 3D MPPCs with fcc, bcc, sc lattices are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in 3D MPPCs with fcc, bcc, sc lattices, and the complete PBGs can be obtained compared to 3D MPPCs containing of the conventional isotropic dielectric. It also is shown that the anisotropic PBGs can be tuned by the ordinary refractive index, extraordinary refractive index, plasma cyclotron frequency, filling factor, and plasma frequency, respectively. The larger relative bandwidth of complete PBG can be obtained by introducing the uniaxial material as 3D MPPCs are with high-symmetry lattices. This also provides a way to design the tunable MPPCs devices.

Reconfigurable designs for electromagnetically induced transparency in solid state plasma metamaterials with multiple transmission windows

A reconfigurable metamaterial analog electromagnetically-induced-transparency-like (EIT-like) effect is theoretically and numerically demonstrated in this paper. The unit cell is composed of a stimulated circular loop element and an unstimulated arc slot element, which are both constructed by semiconductor. The interaction between the two elements of the unit cell leads to a transparency window, resembling a special quantum optical phenomenon as electromagnetic (EM) induced transparency. The proposed designs can realize a continuously tunable EIT-like effect in a broad frequency range from 2.2 GHz to 3.6 GHz by changing the arc slot angle, while the number of EIT-like transmission windows can be configured by increasing the number of arc slots. This scheme which is constructed by solid state plasma (SSP) metamaterial provides an alternative way to realize the tunable plasmonic sensing and make new kinds of reconfigurable devices.

The Wavelength Division Multiplexer Realized in Three-Dimensional Unusual Surface-Plasmon-Induced Photonic Crystals Composed of the Epsilon-negative Materials Shells

In this paper, the dispersive properties and switching state of three-dimensional (3D) photonic crystals (PCs) with diamond lattices, which are composed of the core isotropic dielectric spheres with surrounded by the epsilon-negative (ENG) materials shells inserted in the isotropic dielectric background (air), are theoretically investigated in detail based on a modifled plane wave expansion method. The wavelength division multiplexer can be realized easily by tuning the switching state of such PCs. The equations for computing band structures for such 3D PCs are presented. Our analysis shows that the proposed double-shell structures can obtain the complete photonic band gaps (PBGs) which can be used to realize optical switching by manipulating the radius of core dielectric sphere, the relative dielectric constant of background, the dielectric constant of ENG materials and the electronic plasma frequency, respectively. However, the thickness of the ENG materials shell cannot change the switching state as the radius of core dielectric sphere is certain. Numerical simulations also show that a ∞atband region, and the stop band gaps (SBGs) in (1 0 0) and (1 1 1) directions which are above the ∞atband region can be achieved. The SBGs in (1 0 0) and (1 1 1) directions can also be tuned by the parameters as mentioned above. There also exists a threshold value for the thickness of ENG material shell, which can make the band structures for the 3D PCs with double-shell structures similar to those obtained from the same structure containing the pure ENG materials spheres. In this case, the inserted core sphere will not afiect the band structures. It means that we can achieve the PBGs by replacing the pure ENG materials spheres by such double-shell structures to make fabricate easily and save the material in the realization. It is also noticed that the ∞atband region is determined by the existence of surface-plasmon modes, and the upper edge of ∞atband region does not depend on the topology of lattice. Such presented 3D PCs with double-shell structures ofier a novel way to realize the wavelength division multiplexers.

Bandstop Mechanism of Light Scattering from Morpho Butterfly's Wing

The bandstop of optical scattering from a special photonic crystal-the microstructure of Morpho butterflys wing is investigated in detail in this paper. Firstly, the bandstop characteristic of light scattering from the microstructure of Morpho butterflys wing is investigated with simplified geometry model and finite difference time domain (FDTD) method. Furthermore, the effects of structural parameters on the bandstop characteristic are studied in detail, and the mechanism of the scattering is explained by photonic crystal theory. Numerical results presented will be benefit for the bandstop spatial filter design in the future.