含超导材料Cantor序列一维光子晶体的传输特性

利用传输矩阵法研究了按分形三分Cantor序列构成的一维超导光子晶体的传输特性.数值结果表明,与传统电介质材料构成的光子晶体的频谱不同,这种光子晶体频谱没有展现出自相似性.此外,当构成光子晶体的两种材料的光学厚度相同时,光子晶体的频谱具有明显的周期性,并且在光子带隙中间成对地出现缺陷模.这种特性可以用于设计通道滤波器.     

含特异材料一维超导光子晶体的带隙特性研究

利用传输矩阵法研究了含特异材料的一维超导光子晶体的带隙特性. 研究表明, 这类超导光子晶体同样具有由传统的电介质材料构成的超导光子晶体一样的低频带隙, 且在一定的参数下该低频带隙可以相当宽. 但在一定的结构参数下, 这类超导光子晶体同完全由传统的电介质构成的光子晶体一样不存在低频带隙. 还就超导光子晶体的偏振特性、光子晶体结构参数及环境温度的变化对光子带隙结构的影响进行了研究.关键词：超导光子晶体传输矩阵法特异材料光子带隙     

一维光子晶体禁带特性的研究

应用传输矩阵法研究了一维光子晶体的禁带特性,数值模拟得到了一维光子晶体TE模、TM模和TE/TM模禁带结构,计算结果表明,介质层的厚度发生变化时,禁带宽度发生变化。研究结果为一维光子晶体器件的设计提供了理论依据。     

一维光子晶体色散特性的研究

应用传输矩阵法研究一维光子晶体的色散特性,数值模拟得到了一维光子晶体横电(TE)模、横磁(TM)模的色散特性,研究结果为一维光子晶体器件的设计提供了理论依据.     

掺杂对一维光子晶体带隙传输特性的影响

 基于传输矩阵法,数值研究了掺杂对一维光子晶体带隙特征的影响。研究表明：掺杂时,禁带中心会出现一导带,导带深度会随着掺杂位置、杂质折射率的变化而发生变化。当晶体结构给定时,总存在一个掺杂位置,使其禁带中心的导带深度达到最深;而对于给定的掺杂位置,当杂质折射率为某特定值时,禁带中心同样也会出现一个深度最深的导带,这种特性可应用于滤波器件和光学谐振腔的设计。     

一维电介质-金属光子晶体的光学特性研究

利用传输矩阵方法,研究了一维电介质-金属光子晶体的光学特性,该光子晶体通过在Si/SiO₂组成的电介质型光子晶体中插入一定厚度Al层形成。计算结果表明,金属层的引入可以有效提高反射效率,[Si(46 nm)/SiO₂(60 nm)/Al(10 nm)/SiO₂(60 nm)]5结构的单位周期传输衰减从[Si(46 nm)/SiO₂(120 nm)]5的7.2 dB增大到了20 dB;可以得到更宽频率范围的全方向反射带隙,例如[Si(46 nm)/SiO₂(60 nm)/Al(30 nm)/SiO₂(60 nm)]5结构即可提供550 nm带宽的全方向反射;同时讨论了金属吸收、金属层厚度及插入位置对其光学特性的影响。这种电介质-金属光子晶体有望作为性能优异的光学反射镜得到应用。     

一维光子晶体的透射谱特性

利用传输矩阵法研究了一维光子晶体的透射谱特性,数值模拟得到了可见光波段一维光子晶体中的透射谱特性,计算结果表明可见光波段入射波长变化时,透射谱禁带宽度发生变化。研究结果为可见光波段一维光子晶体器件的设计提供了理论依据。     

外磁场与温度对低温超导光子晶体低频禁带特性的影响

文中用传输矩阵法(TMM)分析了TM波垂直入时,超导光子晶体的低频禁带特性,并讨论了外磁场与温度对禁带的影响.分析结果表明:超导光子晶体存在频率从0开始的低频禁带;当没有外磁场作用时,由于超导中正常态电子的影响,低频禁带的截止频率与温度无关;有外磁场作用时,温度才对截止频率具有可调性.外加恒定磁场时,低频禁带的截止频率随温度升高而减小;而在正常态电子的作用下,温度对处在超导态超导光子晶体禁带截止频率的调节范围相对忽略正常态电子情况下减小.恒温下,通过调节外磁场来控制带隙时,正常态电子的贡献很小可忽略不计;外磁场强度增大禁带截止频率减小.当超导体完全处于正常态时,低频禁带消失.     

含负折射率材料的一维光子晶体的光学传输特性

采用光学传输矩阵方法,模拟研究了由正折射率材料和负折射率材料交替组成的一维光子晶体的光学传输特性.计算了这种含负折射率材料的一维光子晶体的透射谱和色散关系.结果表明,在正入射时,含负折射率材料的光子晶体的带隙要比传统的光子晶体要大得多,并具有狭窄的透射带,从光学薄膜理论的色散关系出发解释了形成上述现象的原因.讨论了在不同的偏振模式下,光以中心波长入射时,反射率随着入射角度的变化关系.发现含负折射率材料的一维光子晶体具有更好的角度特性,可以用来实现对中心波长的全方位反射.     

一维三元异质结构光子晶体反射特性

利用传输矩阵法对一维三元光子晶体异质结构的光学特性进行了研究,讨论了介质层厚无序度对三元结构光子禁带的影响.研究表明,将具有相互交叠光子禁带的一维光子晶体叠加构成异质结,可以有效地增大全角度反射的频率范围,当入射角从0°增大到89°,该结构均可实现从0.410 w/w0到0.654 w/w0宽频波段的全反射;相对于二元结构,三元结构可以减小在实际制作过程中随机误差引起的介质层厚无序对光子带隙的影响.该研究结果可为实现可见光及红外光波段大角度反射器的制备及应用提供理论支持.     

一维磁化等离子体光子晶体非互易特性研究

在理想条件下,为了研究等离子体回旋频率、等离子体频率、等离子体层厚度、周期常数和入射角在TM模式下对一维磁化等离子体光子晶体的非互易特性的影响,用利用传输矩阵法计算得到的TM波正向和反向传播的透射率来研究其非互易特性。研究结果表明,增加等离子体回旋频率和入射角度能够改善非互易特性;而一味地增加等离子体频率和等离子体层厚度将会使得非互易传播特性变得恶化;增加周期常数不能明显地改善非互易传播特性,但是通过改变外加磁场的施加方式能够改善其非互易特性。     

A detailed derivation of eigenvalue equation in two dimensional and three dimensional photonic crystals

A detailed derivation of eigenvalue equation in two dimensional and three dimensional photonic crystals is given by the plane-wave expansion method. Some mathematical formulas such as the rotation of vector, the gradient of scalar, the divergence of the vector, the vector triple product and the conversion between scalar and vector are employed. The eigenvalue equation in photonic crystals has become the important base for obtaining the band structure and the distribution of eigenmode.     

Properties of the defect mode in one-dimensional ferroelectric Si/C60 photonic crystals

In the present paper, a novel photonic crystal (PC) defect mode is designed by inserting a ferroelectric material layer (LiNbO₃) into Si/C₆₀ one-dimensional PCs. The band structure of the ferroelectric PCs is numerically analyzed by the transfer matrix method (TMM). The width of the photonic band gap increases by 80 nm and a defect mode appears at a central wavelength of 680 nm when a 150 nm LiNbO₃ layer is inserted into the Si/C₆₀ PC structure. The defect mode in the band gap shifts linearly with the change in electric field. The defect mode shifts by 11.2 nm toward shorter wavelengths when the thin film is subjected to a DC voltage of 1 KV.     

Complex interaction of polarized light with three-dimensional opal-based photonic crystals: Diffraction and transmission studies

Polarization characteristics of light interaction with the photonic crystal of a-SiO₂ synthetic opals were studied under the conditions of low dielectric contrast. We analyzed 3D diffraction patterns of monochromatic light and calculated optical transmission spectra of oriented samples. The diffraction patterns are found to change with the polarization of incident light, indicating a strong polarization dependence of photonic stop bands in synthetic opals. It is shown theoretically there exists a critical angle, θ_c, of the p-polarized light incident on the (h k l) crystal plane, at which the resonance contribution to Bragg diffraction vanishes.     

时变非磁化等离子体光子晶体缺陷态研究

采用非磁化等离子体的分段线形电流密度卷积(Current density convolution,JEC)时域有限差分(Finite-dif-ferent time-domain,FDTD)算法研究了具有单一缺陷层的一维时变非磁化等离子体光子晶体的缺陷模特性。以高斯脉冲为激励源,通过由算法公式得到的电磁波透射系数讨论了等离子体上升时间对其缺陷模的影响。结果表明,改变等离子体的上升时间和密度可以获得不同的缺陷模。     

Investigation of the linear and nonlinear properties of a Drude model photonic crystal

The optical transmission properties of a one-dimensional Drude model photonic crystal are investigated. The linear wave propagation is studied by the transfer matrix method. Using a delta-function approximation a nonlinear 2-d map is obtained and used to explore the global transmission properties of nonlinear wave propagation in this system. Inclusion of a frequency-dependent refractive index represented by the Drude model results in a considerable modification of the characteristics of the linear and nonlinear wave propagation of the one-dimensional photonic crystal.     

Magneto-optical Faraday effects in dispersive properties for three-dimensional magnetized plasma photonic crystals

The dispersive properties of three-dimensional magnetized plasma photonic crystals composed of homogeneous magnetized plasma spheres immersed in isotropic dielectric host with face-centered-cubic lattices are theoretically studied based on plane wave expansion method, as the magneto-optical Faraday effects of magnetized plasma are considered. The equations for calculating the band structures are theoretically deduced. The photonic band gap and a flatbands region can be obtained. The influences of host dielectric constant, plasma collision frequency, filling factor, external magnetic field and plasma frequency on the dispersive properties are investigated in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the photonic band gap can be manipulated by the plasma frequency, filling factor, external magnetic field and host dielectric constant, respectively. However, the plasma collision frequency has no effects on photonic band gap. The location of flatbands region cannot be tuned by any parameters except for the plasma frequency and external magnetic field.     

Defect and dope selective of transmission properties of 2D photonic crystal

The effects of the defect and doping on the transmission properties are investigated in two-dimensional photonic crystal (PC) with triangular rods using the finite difference time domain (FDTD) method. The results show that the width and the central position of the photonic band gap (PBG) depend on the thickness of rods with defect or composite-defect, and the refractive index of doped dielectric rods. The transmission properties of composite-defect combined with doping are further investigated. The thinner the nested concentric triangular rod and the smaller the refractive index is, the wider the band gaps is.     

Genetic optimization of two-dimensional photonic crystals for large absolute band-gap

A genetic algorithm (GA) is used for the design of two-dimensional photonic crystals with large stop-bands. In this procedure, the unit cell of the crystal with square lattice is assumed to be composed of a number of Si round rods. And the key point to obtain maximum absolute band-gap is using the GA to optimize the radius and center position of each rod in unit cell. In the implementations of GA, the structure of each unit cell is represented by a binary string and the fitness (the absolute band-gap) for each unit cell is calculated by the plane-wave expansion (PWE) method. As numerical examples, we present several GA designs considering different number of round rods in the unit cell as well as the band-gap under the light line. The maximum absolute bandwidth of these optimized band-gaps is 0.1466(2πc/a).