基于多模干涉的二维三角晶格光子晶体分束器

光分束器光接入系统的核心器件,是光子多功能设备和系统的关键构成模块,为满足急速增长的数据通信业务对光分束器的需求,本文在完整三角晶格光子晶体中引入五条平行光子晶体波导组成多模干涉系统,利用自成像效应的多模波导与微腔耦合,提出了一种新型二维三角晶格光子晶体四端口分束器.利用时域有限差分法进行仿真分析,结果表明:在一定范围...     

超短双芯光子晶体光纤偏光分束器

提出了一种基于椭圆双芯光子晶体光纤的偏振分束器,并利用全矢量有限元法分析了偏振分束器长度与结构参数的关系,由此得出了偏振分束器长度随孔间距、占空比和桥路变化的一般规律。研究表明,当椭圆双芯光子晶体光纤偏振分束器结构参数一定时,孔间距越小,桥路宽度越宽,则分束器长度越短;占空比变化对长度影响不明显,但对消光比的影响较明显。进而,通过结构参数的优化,设计出一种超短的椭圆双芯光子晶体光纤偏振分束器,在工作波长1 550 nm处,该分束器的长度仅为0.775 mm,消光比高达50 dB,消光比大于20 dB的带宽覆盖了从1 535~1 565 nm之间30 nm的波长范围,即通信C波段范围。     

基于二维光子晶体的光控分光比可调Y型太赫兹波分束器

在完整的二维三角晶格硅光子晶体中,引入线缺陷和非线性聚合物材料的点缺陷,利用线缺陷模和点缺陷模的耦合作用和非线性聚合物材料的三阶非线性克尔效应,提出了一种基于二维光子晶体的光控分光比可调Y型太赫兹波分束器。采用平面波展开法（PWM）和时域有限差分法（FDTD）,对分光比可调的太赫兹波分束器性能进行了研究。研究结果表明,通过改变控制光的光强,可实现两输出端口分光比可调的Y型太赫兹波分束器。此分束器可实现特定波长的太赫兹波分光,透射率达到98%以上,附加损耗低于0.087 dB,响应时间达到ps量级。该分光比可调的分束器将在未来太赫兹波通信中具有广阔的应用前景。     

A novel polarization splitter based on three-core photonic crystal fibers

A novel polarization splitter based on photonic crystal fibers(PCFs) with three cores of high birefringence is proposed.The 45o linearly polarized light is launched into a core.After a coupling length(about 1500 μm),the xand y-polarized light beams are separated into different cores.When the light is launched into another core,the xand y-polarized light from different cores can be obtained and the degree of separation can be also adjusted.The polarization splitter is highly flexible and adjustable.The lengt...     

基于单平行分束器的偏光干涉系统

为了克服常规偏光干涉系统中核心器件萨瓦板(Savart)偏光镜制作工艺复杂、装调难度高的缺点,解决由于Savart偏光镜装调、加工误差造成的偏光干涉系统条纹混叠和调制度下降的问题,采用了一种基于单平行分束器(SPBS)的偏光干涉系统的方法,分析了系统的结构原理,采用矩阵传递函数推导了经偏光干涉系统出射光的琼斯矩阵及相干叠加强度,得出了和基于Savart偏光镜的干涉系统类似的干涉结果,分析了系统光程差与入射角及入射面的变化关系,并通过实验验证了理论分析的正确性。结果表明,由于SPBS结构简单,不需要多个单元组合,所以不存在装调误差,并且大幅度降低了加工误差。     

Dual-core photonic crystal fiber polarization splitter based on lead silicate glass

Integral imaging is a three dimensional(3D)display technology without any additional equipment.A new system is proposed in this paper which consists of the elemental images of real images in real mode(RIRM)and the ones of virtual images in real mode(VIRM).The real images in real mode are the same as the conventional integral images.The virtual images in real mode are obtained by changing the coordinates of the corresponding points in elemental images which can be reconstructed by the lens array in virtual space.In order to reduce the spot size of the reconstructed images,the diffuser in conventional integral imaging is given up in the proposed method.Then the spot size is nearly1/20 of that in the conventional system.And an optical integral imaging system is constructed to confirm that our proposed method opens a new way for the application of the passive 3D display technology.     

A novel polarization splitter based on octagonal dual-core photonic crystal fiber

A novel polarization splitter based on octagonal dual-core photonic crystal fiber(O-D-PCF) is proposed. The impacts of several fiber parameters on the coupling characteristics of the polarization splitter are investigated by full-vectorial finite element method(FV-FEM) in detail. Through optimizing the fiber configuration, a 4.267-mm-long polarization splitter with a bandwidth of 37 nm is achieved, and its extinction ratio(ER) is as high as 81.2 d B at the wavelength of 1.55 μm. Compared with the hexagonal dual-core photonic crystal fiber(H-D-PCF) based polarization splitter, both ER and bandwidth of the O-D-PCF based one are effectively improved.     

硅基槽波导级联多模干涉耦合器型偏振分束器

提出了一种基于硅基槽波导的级联多模干涉(MMI)耦合器型偏振分束器,由锥形及矩形结构MMI耦合器构成.级联结构使器件长度无需为两偏振模自镜像长度的公倍数,不仅能有效减小器件尺寸,而且提高设计灵活性.同时,利用槽波导的高双折射特性及MMI耦合器的锥形结构,可进一步缩短器件尺寸.分析结果表明,所提器件能够有效实现偏振束分离,两级MMI工作区总长度仅为42μm,准TE与准TM模的偏振消光比分别为29.8和31.4d B,1.55μm波长下的插入损耗分别为0.395和0.699 d B,偏振消光比大于20 d B时光带宽为43 nm,覆盖整个C波段.最后,详细分析了器件关键参数的制造误差对器件性能的影响.     

Y型光子晶体偏振光分束器

基于偏振模式不同的光波在二维光子晶体中的传播特性不同,设计出一个支路半径相同的Y型二维光子晶体偏振光分束器.通过时域有限差分法对该分束器进行数值计算与模拟分析.结果表明,该分束器能够实现TE模和TM模平行、高效分束.当波长为1.55μm的高斯脉冲入射时,TE模透射率可达97%,TM模透射率可达93.5%,且该结构尺寸仅有6.3μm×6.8μm.这些特性使其在未来的集成光路中具有很好的应用前景.     

A novel polarization splitter based on the photonic crystal fiber with nonidentical dual cores

A novel polarization splitter based on photonic crystal fibers (PCFs) with two nonidentical cores is proposed. The two highly birefringent cores are vertically arranged to obtain polarization selective coupling. The horizontal polarization exchanges its energy between the two cores. However, the vertical polarization shows little coupling between the two cores. This is achieved in single-material glass waveguides for the first time to our knowledge. The PCF-based polarization splitter exhibits many advantages such as shorter length, high extinction ratio, and wide bandwidth over its counterparts.     

基于一维光子晶体的偏振分束器

通过设计含缺陷的一维光子晶体,利用特征矩阵的方法计算了在特定频率条件下s光和p光在不同入射角度下的透射率,发现对特定频率的光在一定角度范围内s光和p光具有很高的消光比,且p光具有很高的透射率。说明该一维光子晶体可以作为优良的偏振分束器件。     

矩形晶格结构双芯光子晶体光纤偏振分束器的研究

椭圆形空气孔光子晶体光纤可以产生较高的双折射,使得不同偏振方向的光有不同的耦合长度.将光纤的双折射现象应用于双芯光纤中,可以实现偏振状态的分离.应用平面波扩展法分析了椭圆形空气孔、矩形晶格结构的双芯光子晶体光纤中结构参量对光束不同偏振方向的耦合长度的影响,设计了一种基于椭圆形空气孔、矩形晶格结构的双芯光子晶体光纤偏振分束器.应用全矢量光束传播法分析了这种光纤偏振分束器的性能.结果表明,在1.55 μm工作波长上,长度为1.055 mm的光纤即能实现偏振状态的隔离,隔离度达到-16.9 dB,隔离度＜-16 dB的带宽可达到270 nm.     

双矩形纤芯光子晶体光纤偏振分束器

基于双折射效应设计了一种新颖的纤芯为椭圆空气孔,包层为圆形空气孔的矩形双芯光子晶体光纤偏振分束器。用半矢量光束传播法(BPM)数值模拟了基模情形下该偏振分束器的性能,结果表明:在工作波长为1.55μm,光纤长度为1659μm时,两个纤芯在X、Y方向偏振光的隔离度分别达到了-41.3 dB和-39.1 dB,隔离度小于-10 dB的带宽超过了80 nm,达到了良好的偏振分束性能。同时,模拟了实际加工误差对所设计的偏振分束器的影响,得出在1.55μm的工作波长下,误差达到±7%时,隔离度仍能小于-10 dB,具有较高的实际应用价值。     

Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application

We report that we have successfully designed and fabricated a significantly shortened multimode interference coupler for application in polarization splitter, using a phenomenon that we termed "quasi-state" (QS) imaging effect. First, we identified and analyzed the QS imaging effect, and, based on the QS analysis, designed and fabricated a novel multimode interference (MMI) device with its split length shortened to 1/5 of a normally designed MMI split length. The fabrication is simple and cost effective and the fabricated device shows outstanding characteristics in extinction ratio, signal homogeneity, excess loss, and tolerance in the length of the splitter.     

基于光子晶体方形谐振器的可调谐光信号分离器

在二维光子晶体结构中通过调节光子晶体方形谐振器PCSRs(Photonic Crystal Square Resonators)与波导的耦合长度、耦合宽度、及其耦合柱半径优化设计了光信号分离器.借助于CMT(Coupled-Mode Theory)理论定性分析了两个PCSRs存在相互作用时,结构中波导与谐振腔之间的电磁波耦合性能,用FDTD方法研究了两信道传输工作特性.表明在设计的参数范围中,基于PCSRs的信号分离器具有高正规化传输率、窄带宽、平稳的信号传输强度,中心波长调谐范围宽的特性.该类结构可用于同一中心波长信号的功率二等均分,也可用于不同中心波长信号的分离.该微型结构在片上的光路设计将是一类有潜力的构筑模块,适于光通信领域波分解复用设计、光路集成设计等方面.     

高双折射双芯光子晶体光纤偏振分束器

设计了一种基于双折射效应的新型矩形纤芯光子晶体光纤偏振分束器,通过在矩形晶格结构的光子晶体光纤的每个纤芯中引入一对椭圆来增加结构的双折射。应用全矢量有限元法（FEM）分析了双芯光子晶体光纤中结构参数对双折射和耦合长度特性的影响,数值模拟了该偏振分束器的性能。结果表明:增大椭圆率可以在增大结构的双折射的同时减小耦合长度,并且该分束器在工作波长为1.55 m、传输长度为282 m 的光纤中能够实现偏振状态的隔离,消光比达到最小值-45.42 dB,并且在1.507~1.596 m、带宽为89 nm 的范围内消光比小于-10 dB。     

基于光子晶体正负折射的分束器的误差分析

利用时域有限差分方法,通过数值模拟分别研究了基于光子晶体正负折射原理设计的分束器中介质柱半径和介质柱位置的随机误差对分束器性能的影响,发现当介质柱半径的误差振幅小于0.055倍的介质柱标准半径或者介质柱位置的误差振幅小于0.06倍的光子晶体品格常数时,正负折射光束的能流透射率均保持在20%以上.