平面金属光子晶体波导宽度对导行模的影响

本文用频域有限差分法计算平面正方排列金属光子晶体的TM 模全域带隙图,结果表明当填充比大于0.11 是一 值时会出现多个禁带,适当的引入线缺陷可分别在这些带隙中引入缺陷模,形成光子晶体波导,光子晶体波导支持的电 磁波模式和通道宽度有着密切的关系,通过调节缺陷宽度可以实现单模传输并使单模传输带宽最大化。     

0.35 THz二维光子晶体带通滤波器设计

设计了一种基于二维光子晶体的太赫兹带通滤波器,通过在线缺陷的光子晶体波导两侧引入对称的点缺陷形成谐振腔,在太赫兹频段实现了较好的带通滤波特性。这种二维光子晶体带通滤波器具备较宽的通带带宽,同时还可以通过增加多组对称点缺陷的方式实现多个谐振腔的级联,进一步提高带外抑制特性,可满足太赫兹通信或雷达系统的应用需求,具有良好的应用价值。     

二维光子晶体窄带滤波器研究

由于光子晶体存在带隙,只要在完整的二维光子晶体中引入线缺陷,那么原来处于禁带处特定波长的光也能沿着形成的波导传播,从而该光子晶体就具备了滤波的功能,再在线型波导的一侧设计个点缺陷,利用时域有限差分法分析发现,在缺陷处耦合出来的光不仅仅光强增大了,而且半高宽也变小了,这就与窄带滤波器的功能十分吻合。此外,只要根据光子晶体的晶格常数和椭圆介质柱的半径与窄带滤波器的中心波长关系,通过调整光子晶体的晶格常数和介质柱的半径,就可以改变窄带滤波器的中心波长。     

基于HMSIW的宽带带通滤波器设计

为有效减小C波段基片集成波导的尺寸和插入损耗,提出了一种基于半模基片集成波导的紧凑型宽带带通滤波器。该滤波器引入由单个谐振槽和多个谐振槽组成的缺陷微带结构,并对其性能进行了研究。通过HFSS仿真验证,引入的缺陷微带结构,不仅可以减小插入损耗,而且实现传输零点的引入,改善了阻带特性。该方法设计的半模基片集成波导带通滤波器具有集成度高、体积小、成本低、制造方便等优点,在C波段卫星和雷达中得到了广泛的应用。     

光子晶体波导的非线性局域模

用光子而不是电子作为信息载体 ,最有希望的光学材料是光子带隙晶体。在这种晶体中介电常数的周期结构调制能可控地禁止光波在特定波带中的传播。在光子带隙材料基础上提出的微观光操纵器件中特别感兴趣的是小心制造的浅缺陷 ,这种浅缺陷能在全光微芯片中起波导作用。最近 ,Tokushima等人演示了将 1 .55μm波长的光弯曲成 1 2 0°的波导传播 ,该弯波导是在三角形晶格二维光子晶体中做成。对于用具有非线性响应材料组成的光子晶体或嵌有非线性杂质的光子晶体 ,可以通过改变光强来实现光子晶体波导性质的动态可调。在这种情况下高强度光能通…     

矩形缺陷光子晶体太赫兹波波导的慢波特性

设计了一种工作于太赫兹波段的矩形孔缺陷光子晶体慢波波导。首先分析三角空气孔型光子晶体的带隙特性,引入线缺陷形成波导,并将邻近缺陷空气孔设为矩形,通过分析矩形孔尺寸对波导的带隙结构、群速度的影响,确定孔尺寸;研究缺陷宽度对缺陷模式的影响,并通过优化将缺陷模式频率移到目标频率338 GHz处,最终在布里渊边界处实现了c0/1543(c0=3×108m/s)的低群速度,证明了矩形缺陷光子晶体太赫兹波导良好的慢波特性。     

基于波导与环形腔耦合的多通道光子晶体滤波器

为了解决传统滤波器尺寸大、滤波性能差的问题,本文基于光子晶体线缺陷波导和环形谐振腔的耦合原理,设计了一种新型的多通道光子晶体滤波器.利用平面波展开法和时域有限差分法分别对滤波器的结构和传输特性进行了分析,结果表明:该结构滤波器具有优异的选频功能,可以实现1.5717 μm、1.5834μm、1.5084 μm、1.51...     

二维平板光子晶体微腔与波导的耦合北大核心CSCD

光子晶体是介质介电常数呈周期性排布的结构,具有光子带隙,处于光子带隙中的电磁波无法在其中传播。二维平板光子晶体是通过在衬底上刻蚀周期性排列的空气孔柱而形成的结构,由于其具有优良的控制光传播的特性而得到广泛的研究和应用。介绍了在二维平板光子晶体中引入缺陷形成的光子晶体微腔和波导的方法和性质。通过调整几何参数控制微腔与波导之间的耦合,实现基于二维平板光子晶体的全光开关、光存储、单光子源等光学器件并讨论其在量子光学网络中的应用。     

基于二维光子晶体带隙及自准直效应的光分插滤波器研究

鉴于光子晶体具备控光能力强和响应速度快等优点,设计了基于二维光子晶体带隙及自准直效应的光分插滤波器。将二维的正方晶格介质柱当作材料,并融合光子晶体带隙、自准直效应实现光分插滤波器设计。引入平面波展开法,实现完整周期光子晶体架构求解。引入时域有限差分法,获取晶体中的电场磁场整体分布。模拟结果显示,该结构耦合效率与品质因子良好,且场图模拟与对应结构透射谱拟合度较高,表现出了较强的可实践性。     

多元一维光子晶体滤波器的研究

介绍了一种形式如(ABBA)m(ABBB)m的新型二元特殊复周期结构光子晶体来近似分析研究多元一维光子晶体的滤波特性,并运用光学导纳特征矩阵方法数值分析了这种结构以及它的一种掺杂形式(ABBA)mCn(ABBB)m结构光子晶体的能带特性.研究结果表明,这种新结构的光子晶体的禁带宽度较之几种常见二元结构很大或多出一个大的带隙区,非常适合应用于宽带滤波器;同时在某些频率段出现的透过峰也适合应用于多通道窄带滤波器,在引入掺杂C时,发现C的材料,厚度可以影响窄透过峰的位置及多少,对多通道窄带滤波器的设计也很有帮助.而在使用多种材质进行替代研究后发现,多样化的介电常数对光子晶体的禁带宽度及透过峰的宽窄,位置有一定影响.由于其参数设计简单,很适用于设计不同种类要求的滤波器.     

A tunable wavelength demultiplexer using logarithmic filter chains

This paper proposes a novel wavelength division multiplexer (WDM) demultiplexer design for dense WDM networks. The proposed demultiplexer consists of rectangular shaped periodic frequency filters connected in series. These rectangular filters can be formed with an apodized one-dimensional (l-D) photonic crystal structure on a ridged semiconductor waveguide. A design example is given for such filters. In such designs, we can use a moderate refractive index contrast, in discrete groups of many layers, to achieve the same stop-band width that we would get with a large contrast. Apart from being compact in size, to demultiplex an arbitrary wavelength from N wavelengths, only log₂ N switches and filter stages are required. This type of filter has a large potential to be used in integrated photonic implementation and packet switched dense WDM applications     

基于齿状缺陷地的宽阻带交叉耦合SIW滤波器

提出了一种齿状缺陷地低通传输线结构,该低通传输线由多级齿状缺陷地构成,通过调节齿状缺陷地枝节长度,可以有效调节低通和阻带频率范围。利用该齿状缺陷地结构,级联交叉耦合扇形基片集成波导(SIW)滤波器,该文设计了一款高带外抑制的宽阻带滤波器,与传统SIW带通滤波器相比,其矩形系数K_{40 dB}=2,阻带范围大于2倍的中心频率,具有较好的通带和阻带选择特性。测试结果表明,滤波器的中心频率为10.35 GHz,3 dB和40 dB带宽分别为507 MHz和1.05 GHz,插入损耗优于1.47 dB,与仿真结果基本一致。     

Design of Band-Stop Filters in the Presence of Dissipation

The insertion loss vs. frequency characteristic of equal-element band-stop filters is derived for large as well as small degrees of dissipation, and for any number of resonators. These results are presented as curves for one through eight resonator filters. The equal-element band-stop filter, for small dissipation, is shown to have the lowest pass-band loss for a specified stop-band characteristic of all possible filters that can be represented by a low-pass prototype. Design procedures and examples are explained for waveguide and TEM band-stop filters. This includes selecting the optimum number of resonators, the resonator lengths, and the coupling reactance. Experimental results on C-band waveguide and UHF coaxial filters are presented; the results are in good agreement with the theory. This approach makes possible complete prediction of the filter response and results in lower pass-band loss than could be obtained with previously used approaches.     

Band-Stop Filters For High-Power Applications

There are several advantages to the use of band-stop filters, rather than band-pass filters, in many systems. This is shown to be particularly true when signals at high-power levels must be transmitted or rejected. A formula has been derived which expresses the external Q of each resonator in a band-stop filter in terms of the element values of the normalized low-pass prototype and the parameters of the frequency transformation. The peak power capacity of iris-coupled waveguide cavity filters and TEM filters using capacitively coupled inductive stubs is then determined in terms of the external Q of the first resonator and the dimensions of the resonator. Experimental results given for a waveguide band-stop filter show good agreement with theory.     

异质结构光子晶体微腔实现多通道可调谐滤波

为解决WDM系统中多信道同时滤波问题,设计并研究了缺陷对一种异质结构光子晶体多通道滤波器的调制机制,结果表明:在光子晶体环形滤波通道中引入点缺陷形成复合缺陷,可克服光子晶体环形腔结构的多模特性,实现单通道内的单纵模滤波;对于各个通道,复合缺陷中点缺陷的折射率对输出端透射谐振波长具有调谐作用,且对各通道的可调谐滤波作用彼此独立,随着点缺陷折射率的增大,输出的谐振波长出现红移现象。所设计的异质结构结构光子晶体对WDM系统实现多信道滤波功能提供理论和设计参考。     

Channel drop filter using a single defect in a 2-D photonic crystal slab waveguide

This paper describes a theoretical and experimental analysis of the channel drop filter using a single defect formed near the two-dimensional (2-D) photonic crystal slab waveguide. First, we calculate the transmission spectrum of a 2-D photonic crystal waveguide and show that high transmittance for a wide wavelength range (/spl sim/60 nm) is obtained in the 1.55-/spl mu/m region. We also show that a defect state having a wavelength within the high transmission wavelength range can be formed in the photonic bandgap by introducing a single defect of appropriate radius. Next, we fabricate several devices and show that the emission wavelength from each defect can be tuned by changing the defect radius. The measured tuning characteristics coincide well with the calculated results. From the near-field pattern of the device, we estimate the emission efficiency of the present device at almost a few tens percent. We clarify the structural condition in order to obtain the maximum output efficiency and show that tuning of emission wavelength while maintaining high output efficiency is possible by selecting appropriate defect radius and position. Based on these results, we propose an ultrasmall channel drop filter for a wavelength-division-multiplex optical communication system.     

缺陷对光子晶体透射能带谱的简并效应研究

为了设计高品质、高性能的光学滤波器和光开关,利用传输矩阵法通过数值计算模拟的方式绘制1维光子晶体的透射能带谱,研究和分析了两缺陷之间距离和缺陷的厚度对光子晶体透射能带谱的简并效应。结果表明,当两缺陷之间距离越大,透射能带谱简并效应越明显,当间距增大到一定数值时,出现分立透射峰完全简并现象;当缺陷厚度整数倍增大时,光子晶体透射能带谱出现简并的趋势,但缺陷厚度奇数倍增大与偶数倍增大时,透射能带谱简并速度不一样,前者的简并速度小于后者的简并速度;缺陷厚度无论是奇数倍增大还是偶数倍增大,光子晶体透射能带谱简并的速度均逐渐减小。缺陷对光子晶体透射能带谱简并效应的调制规律,为光子晶体设计新型光学滤波器件、光学开关及其调制机制等提供了指导。