Near-infrared tunable narrow filter properties in a 1D photonic crystal containing semiconductor metamaterial photonic quantum-well defect

The near-infrared (NIR) narrow filter properties in the transmission spectra of a one-dimensional photonic crystal doped with semiconductor metamaterial photonic quantum-well defect (PQW) were theoretically studied. The behavior of the defect mode as a function of the stack number of the PQW defect structure, the filling factor of semiconductor metamaterial layer, the polarization and the angle of incidence were investigated for Al-doped ZnO (AZO) and ZnO as the semiconductor metamaterial layer. It is found that the frequency of the defect mode can be tuned by variation of the period of the defect structure, polarization, incidence angle, and the filling factor of the semiconductor metamaterial layer. It is also shown that the number of the defect mode is independent of the period of the PQW defect structure and is in sharp contrast with the case where a common dielectric or metamaterial defect are used. The results also show that for both polarizations the defect mode is red-shifted as the number of the defect period and filling factor increase. An opposite trend is observed as the angle of incidence increases. The proposed structure could provide useful information for designing new types of tuneable narrowband filters at NIR region.     

Photonic band gap failure in photonic crystal devices

The photonic crystal is an artificial material with periodic dielectric constant and the key factor to preserve their band features is its periodicity. When the number of periods of photonic crystal is decreased the photonic band gap cannot prevent the light of the corresponding frequencies from propagating in photonic crystal, in another word, photonic band gap will be failure. The minimum periods of photonic crystal device which can keep photonic band gap effective in miniaturization process is analyzed, the transmittance spectrum is calculated by the Finite-difference time-domain algorithm (FDTD) [1], the minimum periods is got in the simulation and the reason which affects the minimum periods is analyzed in this paper.     

Photonic band gap of one-dimensional periodic structure containing dispersive left-handed metamaterials

Band structures of one-dimensional(1D)photonic crystals(PCs)containing dispersive left-handed metamaterials are studied theoretically.The results show that the structure possesses a type of photonic band gap originating from total internal reflection(TIR).In contrast to photonic band gaps corresponding to zero average refractive index and zero phase.the TIR gap exhibits sharp angular effect and has no polarization effect.It should also be noted that band structures of transverse electric(TE) and transverse magnetic(TM) mode waves are exactly the same in the PCs we studied.     

Experimental investigation of photonic band gap in one-dimensional photonic crystals with metamaterials

Composite right/left-handed transmission lines with lumped element series capacitors and shunt inductors are used to experimentally realize the one-dimensional photonic crystals composed of single-negative metamaterials. The simulated and experimental results show that a special photonic band gap corresponding to zero-effective-phase (zero-_φeff${\phi }_{\mathrm{eff}}$) may appear in the microwave regime. In contrast to the Bragg gap, by changing the length ratio of the two component materials, the width and depth of the zero-_φeff${\phi }_{\mathrm{eff}}$ gap can be conveniently adjusted while keeping the center frequency constant. Furthermore, the zero-_φeff${\phi }_{\mathrm{eff}}$ gap vanishes when both the phase-matching and impedance-matching conditions are satisfied simultaneously. These transmission line structures provide a good way for realizing microwave devices based on the zero-_φeff${\phi }_{\mathrm{eff}}$ gap.     

Photonic band gap and defect mode from a layered periodic structure with anisotropic nonmagnetic right-handed and left-handed metamaterials

We demonstrate a photonic band gap (PBG) from a layered periodic structure containing anisotropic nonmagnetic right-handed and left-handed metamaterials whose permittivity elements are partially negative. A set of criteria imposed on materials and structures to realize a PBG is derived, and the transmission spectra are also discussed. When a defect layer is introduced, some unusual properties are found in contrast to that of a defect mode in ordinary PBG structures.     

Photonic band gap engineering in 2D photonic crystals

The polarization-dependent photonic band gaps (TM and TE polarizations) in two-dimensional photonic crystals with square lattices composed of air holes in dielectric and vice versa i.e., dielectric rods in air, using the plane-wave expansion method are investigated. We then study, how the photonic band gap size is affected by the changing ellipticity of the constituent air holes/dielectric rods. It is observed that the size of the photonic band gap changes with changing ellipticity of the constituent air holes/dielectric rods. Further, it is reported, how the photonic band gap size is affected by the change in the orientation of the constituent elliptical air holes/dielectric rods in 2D photonic crystals.     

Photonic band structure in a two-dimensional hexagonal lattice of equilateral triangles

In this paper, the plane wave expansion method is used to calculate the photonic band structure (PBS) for the transverse electric (TE) polarization in a two-dimensional hexagonal lattice composed air holes with cross-sections in the shape of equilateral triangles embedded in a GaAs background. We consider that the dielectric constant of GaAs is dependent on both hydrostatic pressure and temperature. Further, an increase can be observed in the width of the photonic band gap (PBG) while the lengths of the sides of the equilateral triangles are increased. When the pressure increases in the presence of a constant temperature, the dielectric constant of GaAs decreases; further, the PBS exhibits a more noticeable shift toward regions of higher frequencies than that observed while the temperature is increased at a given pressure. We also observed that the PBG obtained by rotating the triangular holes by an angle θ increases when compared against the results obtained for the lattice of holes without performing any rotation. In addition, the results obtained using the supercell technique denote that the position and width of the PBG remain unchanged while removing a triangular hole from the structure, denoting the presence of a defective band within the PBG.     

Effect of anisotropy on the photonic band gap and surface polaritons of a one-dimensional single-negative photonic crystal

The effect of anisotropy on the photonic band structure and surface polaritons of a one-dimensional photonic crystal made of uniaxially anisotropic epsilon-negative (ε<0,μ>0) and mu-negative (ε>0,μ<0) metamaterials is theoretically investigated. Two different cases of uniaxially anisotropic epsilon-negative and mu-negative metamaterials are considered. It is found out that for one case of anisotropy, one-dimensional photonic crystal does not have any single-negative band gap. As a result, it can not support the surface polaritons. While, for another case, the structure shows single-negative band gaps. So, the surface polaritons can be excited at the interface of such a photonic crystal. However, these surface polaritons, unlike the isotropic case, are not omnidirectional and they are restricted to a limited rang of the propagation constant.     

Control of photonic band gaps in one-dimensional photonic crystals

The photonic band gaps in one-dimensional photonic crystals (PCs) are theoretically investigated. A new method to broaden the photonic band gaps is introduced. Based on the similar method, a kind of photonic crystals is constructed to generate photonic band gaps with proportioned central frequencies. This technology can be used for designing nonlinear PCs for harmonic generation.     

Entanglement of a two-level atom and its spontaneous emission near the edge of a photonic band gap

The entanglement of a two-level atom and its radiation field near the edge of a photonic band gap is studied by using the quantum entropy. Unlike the free space case, there is a steady-state entanglement between the atom and its spontaneous emission field even when the atomic transition frequency lies outside the band gap. Moreover, the degree of entanglement, which is due to the formation of atom–photon bound dressed state, depends on the detuning of the atomic transition frequency from the photonic band edge and can be controlled by a controllable photonic band gap crystal.     

Eye-protection glasses against YAG laser injury based on the band gap reflection of one-dimensional photonic crystal

Eye-protection glasses against YAG laser injury based on band gap reflection of one-dimensional photonic crystal (PC) is designed and manufactured in this paper. The laser beam (wavelength 1.06 μm) is reflected by the one-dimensional PC (with the transmission 10⁻⁷) and absorbed by the phosphatic glass substrate (with the transmission 1% for 1.06 μm), so the transmission of the device for wavelengths of1.06 μm can reach 10⁻⁹. The glasses have enough capabilities to protect the eyes from injury of ns-YAG lasers whose energy density is 1 J/cm² for all incident angles, and also to avoid a second injury to others from the reflected laser beams. The transmission of the glasses is beyond 70% for the visible lights. The testing data of the eye-protection glasses agree well with the theoretical predictions.     

Diffractionless optical networking in an inverse opal photonic band gap micro-chip

We present a design for a photonic crystal (PC) all-optical micro-chip based on a three-dimensional (3D) inverse opal heterostructure intercalated with a two-dimensional (2D) triangular lattice photonic crystal slab. Within the 2D micro-chip layer, we demonstrate single-mode (diffractionless) waveguiding of light in air, throughout a bandwidth of more than 70 nm near 1.55 μm. This suggests that inverse opal photonic band gap (PBG) materials can facilitate on-chip optical networking functions over the telecommunication frequency band used in current-day optical fibers.     

色散负折射特异介质的1维光子晶体缺陷态

在1维光子晶体中引入色散负折射特异介质,分析了其介电常数和磁导率在微波区（1～10 GHz）与频率的关系。分别对以色散负折射介质为缺陷的正折射率介质光子晶体及以正折射率介质为缺陷的正负折射率介质光子晶体进行了数值仿真,得出了均匀平面电磁波在正入射和斜入射时的透射谱。结果表明:在介电常数和磁导率均为负值的不同禁带中,分别出现了单、双缺陷模。利用透射谱的这一特点,可实现单、双通道滤波。     

色散负折射特异介质的1维光子晶体缺陷态

在1维光子晶体中引入色散负折射特异介质,分析了其介电常数和磁导率在微波区（1～10 GHz）与频率的关系。分别对以色散负折射介质为缺陷的正折射率介质光子晶体及以正折射率介质为缺陷的正负折射率介质光子晶体进行了数值仿真,得出了均匀平面电磁波在正入射和斜入射时的透射谱。结果表明：在介电常数和磁导率均为负值的不同禁带中,分别出现了单、双缺陷模。利用透射谱的这一特点,可实现单、双通道滤波。     

Dual-band metamaterial with a windmill-like structure

A broadband negative refractive index metamaterial based on a windmill-like structure is proposed, and investigated numerically and experimentally at the microwave frequency range. From the numerical and experimental results, effect media parameters are retrieved, which clearly show that two broad frequency bands exist in which the permittivity and permeability are negative. The two negative bands are from 9.1 GHz to 10.5 GHz and from 12.05 GHz to 14.65 GHz respectively, and the negative bandwidth is 4 GHz. Due to the good bandwidth performance, the metallic cell with double negative property obtained in this paper is suitable for use in the design of multiband or broadband microwave devices.     

Temperature-controlled tunable acoustic metamaterial with active band gap and negative bulk modulus

The local resonant band gap and the negative bulk modulus of the acoustic metamaterial with Helmholtz resonators are strongly affected by the temperature of water. In this paper, the acoustic transmission line method (ATLM) is introduced to investigate the influences of the temperature of water on the local resonant band gap and the negative bulk modulus of the acoustic metamaterial. Results show that the relative variations of the local resonant band gap and the negative effective bulk modulus suffering from the change of the temperature of water are approximately equivalent and are up to about 11%. The reason is that the local resonant frequency is proportional to the sound speed of fluid which is strongly effects by the temperature of water. By achieving the unambiguous relationships between these unusual properties of the acoustic metamaterial and the temperature of water, we find that the temperature-controlled acoustic metamaterial with the active band gap and the active negative bulk modulus can be realized in theory. This idea opens a new avenue for the design of the tunable acoustic metamaterial that can modulate the acoustic wave propagation.     

Theoretical study of relative width of photonic band gap for the 3-D dielectric structure

Calculations for the relative width (Δω/ω₀) as a function of refractive index and relative radius of the photonic band gap for the fcc closed packed 3-D dielectric microstructure are reported and comparison of experimental observations and theoretical predictions are given. This work is useful for the understanding of photonic crystals and occurrence of the photonic band gap.     

雪花形晶芯光子晶体光纤

设计一种新型光子晶体光纤，可在300 nm带宽范围内实现近零超平坦色散特性.光纤端面上所有空气孔按照通常的三角形规则均匀排列，中央位置十三个排列成雪花形的空气孔小于其它空气孔，这些孔共同构成光纤的纤芯.这类晶芯型光子晶体光纤与传统光子晶体光纤相比具有较大的模场面积，尤其是，通过最佳化匹配晶芯和包层中的空气孔大小可以在300 nm带宽范围内实现超平坦化色散特性，甚至可得到近零色散的平坦化色散曲线。尽管光纤的晶芯为雪花状，但近场很快会演化为类高斯型场分布.     

Zero permittivity band characteristics in one-dimensional plasma dielectric photonic crystal

We consider the oblique propagation of electromagnetic waves in one-dimensional plasma dielectric photonic crystals, the superlattice structure consisting of alternating plasma and dielectric materials using transfer matrix method. Our results show that photonic band gaps for all polarizations can be obtained in one-dimensional plasma dielectric photonic crystals. These structures can exhibit a new type of band or gap, for the incidence angles other than normal incidence, near frequencies where the electric permittivity of the plasma layer changes sign. This new band or gap arises, from the dispersive properties of the plasma layer, only for TM polarized waves and its width increases with the increasing angle of incidence. This differential behaviour under polarization can be utilized in the design of an efficient polarization splitter. The band characteristic is affected by the plasma width, the plasma density, dielectric width, the dielectric constant of the dielectric medium and angle of incidence.