Band structure and reflectance for a nonlinear one-dimensional photonic crystal

We consider a model for a one-dimensional photonic crystal formed by a succession of nonlinear Kerr-type equidistant spaceless interfaces immersed in a linear medium. We calculate analytically the band structure of this system as a function of the incident wave intensity, and find two main tendencies: the appearance of prohibited bands, and the separation and narrowing of these bands. We consider as well a finite version of this photonic crystal for a limited number of alternating linear and non linear set of stacks for which we calculate reflectance as a function of the electromagnetic wave intensity, band index and number of periods. A system with these features can be constructed by alternating very thin slabs of a nonlinear soft matter material with thicker solid films, which can be used to design a device to control light propagation for specific wavelength intervals and light intensities of the same propagating signal.     

Quantum electron plasma in one-dimensional metallic–dielectric photonic crystal

The interaction of the electromagnetic radiation with one-dimensional photonic crystal consisting of metal and transparent dielectric medium is studied numerically. Dielectric permeabilities of the electron plasma in the metal are considered both in the quantum Mermin and in the classical Drude–Lorentz approaches. It is shown that the reflection, transmission and absorption-frequency zones of electromagnetic radiation appear in the photonic crystal. In addition, the reflectance, transmittance and absorptance optical coefficients for such photonic crystal in the quantum approach differ from those coefficients in the Drude–Lorentz approach.     

Anisotropy of nonlinear optical transmission at the edge of the photonic band gap of an apodized layered medium

The effect of Kerr nonlinearity on the transmission of laser radiation in a one-dimensional photonic crystal has been investigated by the transfer-matrix method, modified to describe nonlinear effects. The crystal under study is a thin-film multilayer structure with a spatial distribution of the refractive index, which makes it possible to eliminate side bands in the transmission spectrum at each side of the photonic band gap and significantly increase the slope of the transmission curve. The transmission spectrum of such a photonic crystal structure has been studied for two opposite directions of laser radiation propagation. The anisotropy of nonlinear transmission is most pronounced near the edge of the photonic crystal band gap, which lies in the near-IR region. The proposed structure, having strong transmission anisotropy and sufficiently low reflection in the forward direction, can operate as an optical diode (analog of an electron diode).     

Floquet-bloch waves in bound one-dimensional photonic crystals

Floquet-Bloch waves in a bound one-dimensional photonic crystal are considered. It is shown that a single Floquet-Bloch wave can be excited in a one-dimensional photonic crystal located between two homogeneous media. An exact solution of the wave equation corresponding to this case is represented in the form of a set of heterogeneous waves. For the case of incidence of the plane wave from a homogeneous medium on a bounded one-dimensional photonic crystal, the functions for the reflection and transmission coefficients are obtained based on the exact solution of the wave equation. It is shown that the transmission function for the one-dimensional photonic crystal has a form similar to that for the traditional Fabri-Perot interferometer and is determined by the interference of the Floquet-Bloch waves excited in the crystal. The evolution of the amplitude profile of the decaying Floquet-Bloch waves and the reflection spectrum of the bounded one-dimensional photonic crystal are considered in the first-order forbidden band.     

外磁场作用下一维光子晶体的光传输特性

采用光学传输矩阵方法,研究了外磁场作用下一维光子晶体的光传输特性.在外磁场作用下,介质介电函数在回旋频率ω.附近受到强烈的调制,使组分材料的色散关系发生明显改变,导致光子晶体的能带发生变化,透射谱出现复杂结构.在光子带隙中出现窄通带,窄带中的光是局域的.这表明,在不改变光子晶体组分材料的条件下,可以通过改变外磁场的大小,调制光子晶体的能带及其光传输性质.     

含负折射率材料的异质结构光子晶体的光学传输特性

利用传输矩阵法研究了正负折射率材料构成的异质结构光子晶体的光学传输特性。结果表明:当入射波正入射时,在这种异质结构光子晶体内出现了光子带隙,并且带隙内出现了3个极窄的透射峰,这是正负交替光子晶体和常规材料构成的同周期一维异质结构光子晶体所不具有的新颖物理特性。计算了这种异质结构光子晶体的透射谱。发现:这3个透射峰不敏感于入射角的变化,而在带隙两侧的透射峰则会随着入射角增大统一向带隙靠近;能带敏感于晶格厚度和周期数的变化。     

光子晶体光纤非线性光谱特性的理论与实验研究

光子晶体光纤具有特殊的导光机制和结构可调性,可以产生奇异的色散特性及高非线性,为非线性光纤光学领域的研究提供了新的条件。受多种非线性光学效应的共同作用,在不同泵浦光脉冲参数条件下,不同结构参数及传输特性的光子晶体光纤能产生丰富的非线性光谱。利用分步傅里叶方法求解非线性薛定谔方程,模拟飞秒激光脉冲在光子晶体光纤中的传输过程,获得输出光谱与入射光脉冲参数(泵浦光峰值功率P、泵浦光波长λ、光脉冲形状、光脉冲宽度T_FWHM)、光纤结构参数(孔间距Λ、空气填充比d/Λ、光纤长度z)、传输特性(色散、非线性系数)的关系,分析拉曼孤子、色散波、自相位调制等非线性效应产生的光谱特性。利用光子晶体光纤包层节区进行非线性光学实验研究,获得了孤子波和色散波的宽带光谱输出。理论分析与实验测量的光谱中都包括了波长0.5 μm附近可见光波段的蓝移色散波、0.82 μm波段的剩余泵浦光、1.1 μm波段的孤子波、2 μm附近的红移宽带色散波。理论分析与实验测量结果一致,阐明光子晶体光纤中非线性光谱产生的物理原理,实现了对宽带光谱的可控输出,为高非线性光子晶体光纤的结构设计、制备及非线性光谱的应用研究奠定基础。     

Field distribution of a light wave near a magnetic defect in one-dimensional photonic crystals

The field distribution of a light wave near a magnetic defect in a one-dimensional photonic crystal is analyzed. It is shown that, by properly varying the magnetic defect thickness or the parameters of the photonic crystal surrounding the defect, one can create a situation where the electric field of a light wave will be localized predominantly inside the magnetic layer or, conversely, in the immediate vicinity of the layer surface. This opens up possibilities for optimizing the Q factor of a magnetic microcavity in the presence of dissipation in the magnetic layer and, hence, for enhancing the linear and nonlinear magneto-optical effects. The possibility of separating the contributions from the surface and volume of the magnetic material to the nonlinear magnetooptical properties by properly varying the field distribution over the defect thickness is discussed.     

Nonlinear transmission and reflection characteristics of plasma/polystyrene one dimensional photonic crystal

Reflection and transmission properties of one-dimensional plasma/polystyrene nonlinear photonic crystal have been investigated theoretically. Reflectance and transmitted amplitude of electromagnetic waves through these periodic multilayered structures are calculated for different intensities of controlling wave. It is found that the reflectance of the proposed structures depends on the intensity of the controlling wave and this property can be exploited in the design of WDM coupler, filter, optical logic gates, etc.     

基于一维光子晶体的全光逻辑门研究

考虑光场分布的影响,利用传输矩阵法研究了含有非线性缺陷的非对称一维光子晶体的透射特性,得到一种新的全光逻辑门的实现方法.由于光场在缺陷层中有着很强的局域,光子晶体的非线性效应得到增强.基于此,分析了场分布和缺陷层折射率的相互作用对光子晶体透射特性的影响,结果表明：通过合理设计,透射特性完全可以达到稳定状态.在此基础上设计了基于一维光子晶体的异或、与等全光逻辑门     

Spin Hall effect of light in one-dimensional photonic crystal

We established a general propagating model to investigate the spin Hall effect of light in one-dimensional photonic crystal. A polarized (spin dependent) Gaussian beam which was incident obliquely through one-dimensional photonic crystal was demonstrated. Having decomposed a polarized Gaussian beam into different plane wave components charactering individual wave vectors, we revealed the transmission coefficient and reflection coefficient of each plane wave which propagates through the one-dimensional photonic crystal. It enabled us to obtain exact solution to the electric field of transmitted and reflected beams, and the analytical formula of light intensity, accordingly. A method based upon the partial differentials with the intensity distribution of the transmitted and reflected Gaussian beams was presented to determine the transverse and longitude shifts explicitly. Spin dependent shifts in one-dimensional photonic crystal provide alternative evidence for the spin Hall effect of light.     

RTCM算法在一维光子晶体缺陷模中的应用

利用RTCM算法研究一维光子晶体的缺陷模.研究了TE波和TM波入射时的情况,通过改变杂质层的光学厚度以及杂质层的折射率从而得出一些有重要指导意义的缺陷模特性.同时对有缺陷的一维光子晶体在窄带滤波器中的应用做了一定程度的探讨.结果表明:正入射时,TE波和TM波的透射率几乎相同,随着杂质层光学厚度的增加,透射峰数目增加,这有助于制作多道窄带滤波器.因此,有缺陷的一维光子晶体可以制作波分复用中的多道滤波器.     

Properties of defect modes in one-dimensional photonic crystals containing two nonlinear defects

Transmission properties of one-dimensional photonic crystal with two nonlinear defects were investigated based on the nonlinear transfer matrix method. From the inspection of the optical bistabilities around different defect modes, it was found that the threshold of bistability for the bonding mode is always lower than that for the anti-bonding mode. When intensity of the incident wave increases bistability could happen at any wavelength larger than the resonance wavelength of the linear anti-bonding mode in the gap. The threshold of bistability increases initially with the wavelength, then decreases sharply in reaching the resonance wavelength of the linear bonding mode. The coupling behavior of the two defects was also discussed, and it was found that the threshold of bistability increases with the distance between the two defects. A flat spectrum similar to that formed in the photonic crystal molecules was obtained under certain incident intensity.     

一维光子晶体的基本周期结构及其禁带特征

本文采用光学导纳特征矩阵方法讨论了光波在一维分层介质的传播特性,分析了一维光子晶体的基本周期结构对光子禁带的特征的影响,指出了这种特性的应用.     

Enhanced optical nonlinearity near the photonic bandgap edges of a cholesteric liquid crystal

The third-order Kerr nonlinear optical effect of a one-dimensional photonic bandgap structure of a cholesteric liquid crystal is investigated. In a femtosecond nonlinear transmission measurement, nonlinear optical changes in the bandgap edges are observed. From analysis of the dispersion relation, Kerr nonlinear coefficients of nematics, forming the cholesteric liquid crystal, are found to be enhanced by 1-2 orders of magnitude through the photonic bandgap structure.     

Optical limitation in two-dimensional nonlinear photonic crystal with triangular lattice

Optical limitation in a 2D nonlinear photonic crystal (NPC) has been studied in this Letter. Since the optical limitation is due to Bragg scattering induced by the variation of nonlinear refractive index, it is sure that the optical limitation can be realized in nonlinear photonic crystal. The light propagation characteristics in a two-dimensional nonlinear photonic crystal with triangular lattice has been calculated by using the finite-difference time-domain algorithm, which is constructed by placing certain number of nonlinear dielectric rods in a linear photonic crystal. The optical limiting effects at 1.300 and 0.504 μm have been obviously obtained for TE polarization and TM polarization, respectively.     

An all-optical switch based on a one-dimensional layered structure with defocusing nonlinearity

The feasibility of an optical switch of femtosecond range controlled by a femtosecond light pulse acting on a nonlinear one-dimensional photonic crystal (a layered one-dimensional periodic structure) is demonstrated by computer simulation. The crystal comprises linear and weakly defocusing layers. It is shown that switching occurs when the peak intensity of the initial pulse exceeds a certain threshold value due to the dependence of the transmission-reflection bands of the photonic crystal on the nonlinearity of the medium.     

干涉原理在光子晶体中的应用

从理论和实验上分析了光子晶体环形腔的能量传输.在光子晶体中引入环形结构，以干涉原理为基础，改变其中的内部参数使之满足一定的条件，从而实现了频率的选择传输.用多重散射的方法计算了这种结构的透过谱，并与实验测得的透过谱进行了比较，两者相符较好. 关键词： 干涉原理 光子晶体 环形腔     

光子晶体多通道可调谐滤波器的理论研究

为了实现光子晶体的多通道滤波,对设计出的一维掺杂光子晶体进行了数值计算和理论分析。结果表明：多通道透射峰的波长与空气膜厚度呈线性变化,不同厚度的空气膜可以截到数目不同的透射峰,多通道透射峰的半高宽随光子晶体折射率n₂的增加而减小。以此为基础,设计出滤波通道波长的可调范围达60nm,滤波通道半高宽的可调范围为1nm～5nm,滤波通道透射峰值大于0.98的一维光子晶体三通道可调谐滤波器。     

Eigenwaves in one-dimensional photonic crystals with gain

The dispersion characteristics of a one-dimensional photonic crystal are analyzed in detail on the basis of the exactly solvable Kronig-Penney model for the particular case of a periodic system consisting of an infinite number of insulator-air layers arranged in the direction of propagation of radiation. An analytical solution is obtained, and the behavior of eigenwaves near the edges of the photonic band is thoroughly studied. The behavior of roots on a complex plane is qualitatively analyzed with the use of approximate dispersion characteristics obtained via expanding the solution of the wave equation in series in terms of the harmonics of the lattice spacing. It is shown that, despite the amplifying properties of the material, no gain in the photonic band gap is present, because of the interference quenching of waves.