基于磁化等离子体缺陷层的一维新颖可调谐的光子晶体滤波特性

将磁化等离子体填充到一维光子晶体的缺陷层,构成了一种新颖可调谐的滤波器。讨论了TM波情况下滤波器的滤波特性,并推导了TM波下磁化等离子体传输矩阵。通过改进的传输矩阵方法分析得到:在不改变光子晶体结构的情况下,通过改变等离子体频率和外磁场可以实现滤波通道在光子禁带内较大带宽范围的移动,同时禁带中滤波通道出现的数目也能被等离子频率与外磁场的大小控制。     

非磁化等离子体光子晶体缺陷态的研究

采用时域有限差分法中的分段线性电流密度卷积算法,研究具有单一缺陷层的一维非磁化等离子体光子晶体的缺陷模特性.从频域角度分析得到微分高斯脉冲的透射率,并讨论该光子晶体的缺陷层介电常数、厚度、位置、光子晶体的周期常数和等离子体参数对其缺陷模的影响.结果表明,改变以上参数可获得不同的缺陷模. 关键词： 时域有限差分法 非磁化等离子体光子晶体 缺陷模     

The effect of random variations of structure parameters on photonic band gaps of one-dimensional plasma photonic crystals

The electromagnetic properties of one-dimensional plasma photonic crystals influenced by random perturbation of structure parameters are studied through transfer matrix method in the paper. The random perturbation of thicknesses of layers as well as plasma frequency of layers can influence the electromagnetic properties of one-dimensional plasma photonic crystal. The random perturbation of thicknesses of layers tremendously impacts the band structure of one-dimensional plasma photonic crystals in high frequency domain. The random perturbation of plasma frequency, however, contributes to the moving of a cutoff frequency in the low frequency domain. The position of the defect mode of one-dimensional plasma photonic crystal randomly moves due to the random perturbations. The effect of random perturbation of plasma frequency is more significant than that of random perturbation of thickness of layers, which alters not only the transmittance but also the position of the defect mode. An improved quality factor and a shortened moving distance of the defect mode are both acquired by increasing the period number. And then this work may provide a crude but useful instrument in analyzing disordered 1DPPCs.     

对称双缺陷光子晶体的可调谐滤波特性分析

基于光子晶体的光子局域特性,并利用光子晶体的介观压光效应,提出了一种新型的双通道可调滤波器结构.采用传输矩阵法对该滤波器的光学传输特性进行了理论推导,建立了透射谱与光子晶体结构参数的关系,讨论了介观压光效应对双缺陷光子晶体透射谱的影响,并对所设计的光子晶体结构进行了数值模拟.结果表明:随着入射角度的增大,缺陷峰发生蓝移.随着各介质层折射率或几何厚度的增加,缺陷峰发生红移.当光子晶体发生轴向拉伸应变时,缺陷峰的位置向长波长移动,但缺陷峰的峰值大体不变,从而验证了此滤波器的可调节性.该光子晶体滤波器结构紧凑,可调谐性好,为光子晶体激光器及传感器的设计提供了一定的理论参考.     

Specific features of the emission of chiral photonic crystals with an anisotropic defect: I. Thickness effects

The specific features of defect modes of chiral photonic crystals with an anisotropic defect have been investigated. Peculiarities of the spectra of polarization observables of the system under consideration are analyzed at different thicknesses of the defect layer. It is shown that single refraction occurs in a defect mode, even though the system is anisotropic and inhomogeneous. We also investigated the specific features of the spectra of the photon density of states, light intensity at the defect center, and the Q factor of defect modes at different thicknesses of the defect layer and chiral photonic crystals. It is shown that the lasing wavelength of chiral photonic crystals with an anisotropic defect enriched in laser dyes (resonant atoms) can be controlled in a different way: by varying the defect layer thickness. It is shown that this system can operate as a narrow-band filter (mirror) with a controlled frequency width and location of the total transmission (reflection) range on the frequency scale.     

横磁模式下二维非磁化等离子体光子晶体的线缺陷特性研究

采用等离子体的分段线性电流密度卷积时域有限差分算法研究了横磁波入射时具有单一线缺陷的二维非磁化等离子体光子晶体的缺陷模特性. 从频域角度分析得到微分高斯脉冲的透射系数,并讨论该光子晶体的晶格常数、介质圆柱半径、周期常数、缺陷层参数和等离子体参数对缺陷模特性的影响. 结果表明,改变周期常数、缺陷层位置和等离子体碰撞频率不会改变缺陷模的频率,改变缺陷层介质圆柱的相对介电常数、半径和缺陷层到介质层的中心距离可以在不改变禁带宽度的前提下实现对缺陷模的调节,改变晶格常数、介质圆柱半径和等离子体频率能同时实现对禁带宽度和缺陷模的调节. 关键词： 等离子体 光子晶体 缺陷模 时域有限差分算法     

Plasma photonic crystals numerical and filter characteristics analysis based on symplectic algorithm

From the Maxwell equation, the method of symplectic finite-difference time-domain is applied in analyzing one-dimensional plasma photonic crystal. The propagation process of electromagnetic pulse in one-dimensional vacuum plasma photonic crystal structure is simulated by symplectic algorithm discrete in 2nd order time 2nd order space (T2S2), and 2nd order time 4th order space (T2S4) respectively. Then, from the perspective of frequency domain, the reflection coefficient of the plasma–vacuum photonic crystals is analyzed. The results show that the symplectic finite-difference time-domain method is accuracy and correctness. In the end, the filter characteristics of the plasma photonic crystals (PPCs) are analyzed in different thickness of plasma.     

可见光波段SiO2/CdSe一维光子晶体及缺陷模的研究究

采用SiO2/CdSe构建了可见光波段一维光子晶体结构,并在其中引入LiTaO3缺陷层。利用传输矩阵法,分析了电磁波在无缺陷与含LiTaO3缺陷层两种光子晶体中的带隙结构,系统地研究了缺陷层参数对光子晶体可见光波段带隙结构的影响规律。计算结果表明：LiTaO3的引入,有利于带隙宽度的增加,调整缺陷层结构参数,缺陷模的位置可在不同颜色区域出现,如红光、黄光等缺陷模。该结构有望用于制作可见光波段的滤波器。     

Band gap characteristics of plasma with periodically varying external magnetic field

The reflectance characteristics of a one-dimensional periodically magnetized plasma structure is studied by using the transfer matrix method. It is found that this system has the band gap characteristics of photonic crystals, so we also name it a plasma photonic crystal. The results show that the gap location and gap width can be controlled by the incident angle. If the external magnetic field is small, the gap location and gap width change significantly with incident angle, while they change only slightly when the external magnetic field is sufficiently large. The collision frequency has little effect on the gap location and gap width while it makes the amplitude of reflectance and transmission decrease. This new type of plasma photonic crystal could have potential applications in designing tunable photonic crystal devices.     

铁电液晶缺陷光子晶体调谐滤波器的设计

将铁电液晶作为缺陷层引入一维光子晶体中,用电场改变液晶分子的取向,形成光子晶体快速可调谐滤波器.用传输矩阵法研究了铁电液晶缺陷光子晶体的可调谐滤波特性,计算了电压和液晶材料参量对滤波器透射谱的影响.结果表明:改变电压能容易改变光子晶体滤波器透射峰的位置、强度、个数和带宽,实现良好的调谐滤波功能.     

GCLM缺陷光子晶体带隙结构及滤波特性

研究了以GCLM（the generalized Cantor-like multilayer）结构作为缺陷的光子晶体带隙结构和滤波特性.通过调整缺陷结构参量,可以得到通信波段1 300 nm~1 550 nm附近的窄带滤波窗口.滤波窗口透过率接近100%,而窗口以外的透过率在0.01以下.缺陷结构产生的Cantor分布,对光子晶体的透射特性产生很大影响,通过调整GCLM的结构,可以控制带隙的宽度及带隙中滤波窗口的数量和位置.和其他一维光子晶体相比,这种滤波特性能更好地应用在CWDM中.     

基于等离子体缺陷层的一维可调谐微波光子晶体滤波特性

等离子体填充到一维介质-真空微波光子晶体的缺陷层构成一种可调谐单通道滤波器.据等离子体的强色散特性,其等效折射率与电磁波频率及等离子体频率等参数有关,因而可以通过改变等离子参数,使一维微波光子晶体缺陷层的谐振频率发生偏移,实现微波光子晶体的可调谐滤波特性.介质层和等离子体层分别采用了时域有限差分（FDTD）算法及分段线性电流密度卷积时域有限差分（PLJERC-FDTD）算法.数值模拟表明,通过改变等离子体频率可以实现滤波通道在光子禁带内较大带宽范围的移动. 关键词： 等离子体 微波光子晶体 可调谐滤波     

时变磁化等离子体光子晶体光子局域态分析

采用磁化等离子体的分段线形电流密度卷积(Piecewise Linear Current Density Recursive Convolution,PLCDRC)时域有限差分(Finite-Different Time-Domain,FDTD)算法研究了具有单一缺陷层一维时变磁化等离子体光子晶体的光子局域态特性。以高斯脉冲为激励源,用算法公式所得的电磁波透射系数来讨论了等离子体上升时间对其缺陷模的影响。结果表明,改变等离子体上升时间和密度可以获得不同的缺陷模。     

Dispersion properties of two-dimensional plasma photonic crystals with periodically external magnetic field

Dispersion properties of two types of two-dimensional periodically magnetized plasma array structures with square lattices have been investigated by using plane wave expansion method. It is found that two different regions of flatbands and photonic band gaps occur in the TE polarization due to the external magnetic field. The two types of system can be seen as a kind of unusual plasma photonic crystals. The results show that not only the location of flatbands but also the position and bandwidth of photonic band gaps can be tuned by external magnetic field. The cutoff frequency decreases as external magnetic field increases. The edge of two different of flatbands regions and cutoff frequency shift downward to lower frequencies obviously with increasing plasma collision frequency, while they shift upward to higher frequencies notably with increasing plasma frequency. The filling factor has little effect on the location of flatbands regions. The width of flatbands regions and photonic band gaps are almost unchanged by increasing filling factor, but the number of ominidirectional photonic band gap for type-1 structure plasma photonic crystals can be effectively controlled by adjusting filling factor. It is worth to be noted that the first band gaps above the cutoff frequencies in Г–X and Г–M direction for two types of PPCs can be modulated by the parameters as mentioned above, and the relative bandwidth of band gap in Г–X direction is wider than the one in Г–M direction. The results may provide theoretical instructions to design new tunable photonic crystals devices.     

Transmission properties of photonic quantum well composed of dispersive materials

The transmission properties of one-dimensional photonic quantum well structure produced by inserting defect layers into dispersive photonic crystals have been investigated. These photonic crystals are stacked alternatively with two kinds of dispersive material layers. The inserted layers structure is another kind of dispersive photonic crystal. It has been turned out that the confined states are quantized.     

磁化等离子体光子晶体缺陷态的研究

采用磁化等离子体的分段线性电流密度卷积时域有限差分(PLCDRC-FDTD)算法研究具有单一缺陷层的一维磁化等离子体光子晶体的缺陷模特性. 从频域角度分析得到微分高斯脉冲的透射率,并讨论该光子晶体的缺陷层厚度、位置、周期常数和等离子体参数对其缺陷模的影响. 结果表明,改变位置和周期常数不会影响缺陷模的频率,改变缺陷层的厚度可以增加缺陷模数,改变等离子体参数能同时影响缺陷模的频率和峰值. 关键词： 磁化等离子体光子晶体 光子晶体 缺陷模 时域有限差分法     

用转移矩阵法数值研究二维正方介质柱光子晶体的传输特性

利用转移矩阵方法对二维正方介质柱光子晶体的传输特性进行了研究,数值计算研究了不同晶格、同一晶格柱体截面面积不同、放置方位角不同时光子晶体的传输特性。数值结果表明光子禁带的宽度与中心频率和晶格结构有很大关系,正方晶格更易形成平坦光子禁带,柱体截面面积大,则形成的禁带较宽,在其他因素相同的条件下柱体放置的方位角对光子禁带有重要影响。数值研究表明在正方介质柱下设计宽平坦光子禁带时,可以首先考虑正方晶格结构,其次设法使柱体截面尽量大一些,最后可通过柱体放置方位角来微调光子禁带的宽度与中心频率以达到设计要求。     

Approximate analysis and design of rectangular-lattice photonic crystals

We present a theoretical analysis of wave propagation in rectangular- and square-lattice photonic crystals by approximating the arbitrary refractive-index function with a staircase profile. This profile has a number of tunable parameters that allow one to fit the band structures of the staircase and the desired structure over a large frequency range. The staircase profile is such that its corresponding two-dimensional wave equation decomposes into two one-dimensional equations by means of a constant decoupling parameter. We show that basic features of the band structure and Bloch waves in photonic crystals can be analyzed theoretically through this simple approximation.     

Compton散射对磁化等离子体光子晶体缺陷模密温特性的影响

应用多光子非线性Compton散射模型和有限时域差分法,对Compton散射对磁化等离子体光子晶体缺陷模密温特性的影响进行了理论分析和数值模拟。结果表明,与Compton散射前的情况相比,Compton散射使低温低频处光子禁带中存在缺陷模的明显度降低,缺陷模频率增大,缺陷模和透射率峰值减小;使高温高频处缺陷模和透射率峰值、缺陷模频率显著增大,禁带宽减小,缺陷模位置向高频方向移动。随着电子密度的增大,散射减小了禁带增大效应和缺陷模减小效应,增强了缺陷模频率增大效应;随着电子密度的降低,散射增强了禁带变窄效应、缺陷模峰值增大效应和缺陷模频率减小效应。利用Compton散射,可实现对缺陷模密温特性的有效控制。     

含复合缺陷层的光子晶体的光学特性

运用传输矩阵法研究了在一维光子晶体中插入缺陷层的透光特性。在无缺陷层的一维光子晶体中能产生467~510 nm、1 279~1 715 nm两处明显的光子带隙。重点研究了插入缺陷层后,在1 279~1 715 nm的光子带隙中缺陷层厚度和入射角度大小分别与透射光谱变化的关系。研究发现：缺陷模的位置对入射角变化很敏感;出现缺陷模的数量和插入缺陷层的数量相同;一维光子晶体厚度的增大不会改变缺陷模的数量和位置,只改变透射峰的宽度和透射率。