Evidence of Bloch wave propagation within photonic crystal waveguides

We report in this paper results obtained from characterizations of photonic band gap waveguide, using near field optical microscopy. We will show evidence of a Bloch wave propagating within our W1 photonic crystal waveguides (PCWs) structure, using a 2D Fourier transform approach. The processed image will then be compared to simulations obtained from plane wave method. This comparison exhibits that near-field measurements, using tapered optical fibers as probes, are mainly sensitive to the electric field propagating within the structure. PACS 42.25.-p; 42.30.Va; 42.770.-Qs; 42.82.-Et     

Monochromatic infrared wave propagation in 2D superconductor-dielectric photonic crystal

Anomalous infrared monochromatic transmission through superconducting cylinders embedded in a dielectric and dielectric cylinders embedded in a superconductor is found. The transmitted frequency corresponds to the localized photonic mode in the forbidden photonic band. This localized mode appears when the symmetry of the photonic crystal is broken by a defect. This defect can be formed when supercon-ducting cylinder is removed from the node of the ideal two-dimensional lattice of superconducting cylinders in dielectric medium or one dielectric cylinder placed out of the node of the lattice of the dielectric cylinders in superconducting medium. The corresponding frequency was calculated for the YBa₂Cu₃O_{7 − δ} supercon-ducting cylinders in vacuum.     

各向异性超常材料中倒退波的传播研究

研究了完全各向异性超常材料中的倒退波传播现象,得到了在材料本征轴和传输轴成任意角度情形下倒退波形成的条件,分析了超常材料的介电张量和磁导率张量、电磁波的偏振方式对倒退波形成和传播的影响. 在此基础上,进一步分析了几种不同色散曲线关系的各向异性超常材料中倒退波的产生情况,获得了电磁波波矢和坡印亭矢量(能流)夹角的具体表达式和倒退波传播的一般性结论. 此外,还研究了近零介电常数超常材料中倒退波的传播特性,发现在此类超常材料中倒退波只能是完美倒退波. 关键词： 超常材料 负折射 倒退波 各向异性     

Optical control of light propagation in photonic crystal based on electromagnetically induced transparency

A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency(EIT).The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a threelevel atomic system coupled by standing wave.We show an accurate theoretical simulation via transfer-matrix theory,automatically accounting for multilayer reflections,thus fully demonstrate the existence of photonic crystal structure in atomic vapor.     

Optical trirefringence in photonic crystal waveguides

We demonstrate that 2D photonic crystals can possess optical trirefringence in which there are six field orientations for which linear incident light is not perturbed on reflection or transmission. Such a property is rigorously forbidden in homogeneous nonmagnetic dielectrics which can possess only optical birefringence. We experimentally demonstrate this phenomena in silicon-based mesostructures formed from photonic crystal waveguides embedded in a Fabry-Perot cavity. Multirefringence is controlled by the presence of submicron dielectric patterning and is well explained by an exact scattering matrix theory.     

Anomalous propagation loss in photonic crystal waveguides

Propagation loss can occur in photonic crystal waveguides without complete optical confinement. We employ a highly efficient transfer-matrix method which allows for accurate and reliable extraction of the propagation loss even at an extremely low level. The results for a two-dimensional photonic crystal waveguide shows that the loss exponentially decays via the waveguide wall thickness. An anomalous phenomenon is found where the loss for guided modes near the upper band gap edge can be several orders of magnitude smaller than that for modes in the middle of the band gap. This anomaly can be well explained by the localization degree of guided modes at different frequency domains.     

Transmission properties in Fibonacci quasi-periodic photonic crystal containing negative-zero-positive index metamaterials

The transmission properties in Fibonacci quasi-periodic photonic crystals containing negativezero-positive index metamaterials(NZPIM) are investigated systematically. Because of linear dispersion, an asymmetric band gap appears near the optical Dirac point(DP) only at an oblique incidence. Zero-■ gaps and Bragg gaps exist when the refractive indexes of NZPIM are negative and positive, respectively. We also obtain gaps induced by total reflection on both sides of the DP gap. The corresponding Goo...     

含特异材料光子晶体隧穿模的偏振特性

构造了由普通材料A(SiO₂)和电单负材料B组成的(AB)^N(BA)^N型一维光子晶体.数值计算表明原禁带的1907.3 nm处出现了一个十分尖锐的隧穿模. 入射角增加,该隧穿模的透射率和半峰全宽度均保持不变,但位置发生蓝移, 入射角在15°-65°的区间内,移动率的绝对值 |dλ/dθ| 较大.当B介质的磁导率μ_B 从5增加到10时,只是隧穿模的位置发生了红移. 介质的几何厚度增加时,隧穿模的透射率不变,但其位置红移明显,半峰全宽略有增加.     

Wave propagation in double-period quasi-regular one-dimensional photonic crystals composed of single-negative metamaterials

In this paper, we theoretically study the propagation of electromagnetic waves in one-dimensional double-period quasi-regular structures consisting of negative-permittivity and negative-permeability metamaterials. A Drude-type dispersive response for both permittivity and permeability of single-negative metamaterials is considered. From the numerical results performed by transfer matrix method and effective medium theory, it is found that double-period photonic crystals can exhibit an omnidirectional gap at given microwave frequency. Such an omnidirectional gap is insensitive to incident angle and polarization, and is invariant upon the change of scale length. It is also found that this gap exists in all double-period sequences, and it is independent of structure sequence. Moreover, electromagnetic field distributions in this structures show that the fields are localized at each interface of two media. These results can lead to further applications of quasi-regular structures.     

Lateral stress-induced propagation characteristics in photonic crystal fibres

Using the finite element method, this paper investigates lateral stress-induced propagation characteristics in a photonic crystal fibre of hexagonal symmetry. The results of simulation show the strong stress dependence of effective index of the fundamental guided mode, phase modal birefringence and confinement loss. It also finds that the contribution of the geometrical effect that is related only to deformation of the photonic crystal fibre and the stress-related contribution to phase modal birefringence and confinement loss are entirely different. Furthermore, polarization-dependent stress sensitivity of confinement loss is proposed in this paper.     

一维反铁磁光子晶体光学双稳态效应研究

基于传递矩阵方法和光局域化原理, 本文研究了一维反铁磁光子晶体共振频率附近光学双稳态效应随电磁波入射角、 外磁场强度及电介质层数的变化.研究发现, 当外磁场为1.0 kG(1 G=10^-4 T)、电磁波小角度入射时, 反铁磁材料高低共振频率附近均可探测到光学双稳态效应; 当电磁波大角度入射时, 仅在高共振频率附近探测到光学双稳态效应. 然而, 当外磁场强度增加到2.0 kG时, 由于反铁磁材料的高低共振频率向两侧移动, 低共振频率附近缺失的光学双稳态频率窗口又被有效激发. 此外, 电磁波小角度入射时, 电介质层数在低共振频率附近对双稳态效应影响较明显.     

Optical sensing with photonic crystal fibers

A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long‐period gratings and interferometric structures; the fourth one reports applications of these fibers for gas and liquid sensing; finally, the last section focuses on the exploitation of nonlinear effects in photonic crystal fibers for sensing.     

Comparison of photonic crystal narrow filters with metamaterials and dielectric defects

The photonic band-gap of the two kinds of 1D photonic crystal structure which is composed of the form of (AB) ^N1 C ^m (BA) ^N2 , one with a metamaterial defect layer (MDL) and the other one with a dielectric defect layer (DDL) are studied. Our results show that in both cases, where there is only one defect layer, m=1, no defect mode exists, but for two defect layers (m=2) there is a single defect mode which is centered in the middle of the band-gap. The width of the defect mode in DDL is narrower than that in MDL. For a number of defects of more than two (m>2) and even, in both of the MDL and DDL structures, there is only one defect mode. For m>2 and odd, the defect mode in the MDL vanishes, but for DDL there is two defect-mode symmetrically centered in the middle of the band-gap. The effects of the defect layers refractive index value, the periodicity number of the structures and the incident angle on the properties of the defect modes and the transmittance spectrum are discussed.     

Broadband wave plates: Approach from one-dimensional photonic crystals containing metamaterials

Broadband wave plates working in subwavelength scale are realized by one-dimensional photonic crystals containing negative-index materials. It is demonstrated that the phase shift of reflected wave as a function of frequency changes smoothly within the stop band of the photonic crystal, while it changes sharply within the pass band. In the stop band, the difference between the phase of TE and that of TM reflected wave could remain constant in a rather wide frequency range. These properties are useful for designing compact wave plates or phase retarders which can be used in broad spectral bandwidth.     

Wave propagation in a one-dimensional photonic crystal with metamaterial

This paper deals with the study of the transmission of electromagnetic waves through a one-dimensional multilayer periodic structure consisting of alternating slabs of negative- and positive-index media. It also focuses on the behavior of the transmission with the angle of incidence for both polarizations. The proposed structure works as a tunable p-polarization filter i.e. a filter which completely blocks the s-polarized wave but partially allows the p-polarized wave to pass through it for an angle of incidence greater than 20 ^°. For angles of incidence less than 50 ^° the structure works as a tunable edge filter.     

Continuous wave photonic crystal laser in ultraviolet range

It is shown that photonic band-gap (PBG) structures have great potential for the development of widely tunable continues wave and/or mode-locked ultrashort-pulse all-solid-stale lasers in UV and optical ranges. The basic idea is to decrease the laser threshold via inhibition of radiative decay of an upper laser level by embedding an active medium into spatial structure having PBG at the frequency of laser transition. This technique provides favorable conditions for coherent suppression of the excited state absorption crucial for short-wavelength solid-state lasing. It also resolves the laser gain dilemma, providing combination of high emission cross-section and large population inversion. Different designs of 2D and 3D photonic crystal laser are proposed.     

Semianalytic treatment for propagation in finite photonic crystal waveguides

We present a semianalytic theory for the properties of two-dimensional photonic crystal waveguides of finite length. For single-mode guides, the transmission spectrum and field intensity can be accurately described by a simple two-parameter model. Analogies are drawn with Fabry-Perot interferometers, and generalized Fresnel coefficients for the interfaces are calculated.     

Light propagation in highly birefringent photonic liquid crystal fibers

Photonic liquid crystal fibers have already been demonstrated as a promising perspective for creation of new classes of dynamically tunable optical fiber devices. By combining different geometries of photonic crystal fibers with a variety of different liquid crystals it is possible to obtain a new generation of fibers with dynamically tunable properties, e.g., transmission spectra, attenuation or dispersion. In this paper, tunable birefringence in a commercially available highly birefringent Blazephotonics PM-1550-01 photonic crystal fiber selectively filled with a low birefringence liquid crystal has been experimentally demonstrated. Theses experimental results have been compared with simulations based on the multipole method.     

含奇异材料的掺杂一维光子晶体色散关系和空间局域度理论

给出了描述掺杂的一维光子晶体结构缺陷态的变化规律及其空间局域度特性的理论表达式.该式对由具有任意色散关系材料组成的、中间掺杂、两边对称的一维光子晶体结构均成立.通过研究含奇异材料的光子晶体组态发现，当缺陷层材料为右手材料时，光子带隙中缺陷态的频移方向随缺陷层厚度的增大而红移；当缺陷层材料是左手材料时，频移方向刚好相反，表现为蓝移.该缺陷态的空间局域度只与两边对称结构有关.两边对称结构含奇异材料的光子晶体的缺陷态比传统右手材料的结构具有更强的空间局域度.     

Back-propagating surface polaritons of a one-dimensional photonic crystal containing single negative metamaterials

The existence of the surface polaritons at the interface separating a semi-infinite uniform left-handed metamaterial and a one-dimensional photonic crystal composed of alternating layers of two kinds of single-negative materials is theoretically investigated. The dispersion characteristics of the surface polaritons are analyzed and demonstrated that in the presence of metamaterial, the surface polaritons are sensitive to light polarization, so that there exist only backward TM-polarized (or TE-polarized) kind of the surface polaritons depending on the ratio of the thicknesses of the two periodic stacking layers. The existence regions of the surface polariton modes are determined for both TM-polarized and TE-polarized surface polariton modes.