共查询到20条相似文献,搜索用时 78 毫秒
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三个非平行波导间的耦合 总被引:3,自引:3,他引:0
提出一种分析非平行波导的简明方法…耦合系数推广法,把非平行波导几何图形的变化直接转化成波导耦合系数中波导间距的变化.即对耦合系数进行了巧妙的推广.把波导间距的变化以指数的形式潜人到耦合微分方程中,建立了非平行三波导系统的耦合方程。这些耦合方程包含了非平行波导传输的全部信息,即非平行波导输出光的振幅和相位,非平行传输波导的长度及其夹角.非平行波导输人端口的间距,能量转换与波导参量的关系等。对这些微分方程作巧妙的数学变换,得到非平行三波导耦合系统输出光的完整分析解,分析和讨论了对称和不对称输人初始条件下三个非平行波导的耦合情况。由此可以优化非平行波导的设计参量。 相似文献
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利用一维变周期谐振腔阵列和非线性缓变边界,可以实现光波从脊波导到光子晶体平面波导 (PCW)的高效耦合.基于平面波展开法(PWE)和时域有限差分法(FDTD),深入分析和讨 论了普通脊波导、2D-PCW结构和本征模以及工作模式、缓变边界形状等对耦合效率的影响, 从而得出光波从脊波导到2D-PCW、再返回脊波导的统一图景.指出考虑模式转换和采用缓变 边界条件可以极大提高PCW与脊波导间的耦合效率.对PC-PW边界采用线性和非线性缓变结构 进行了仿真,讨论了边界缓变程度对耦合效率的影响.结果表明,采用模式耦合和PC-PW余弦 缓变边界时的耦合效率在较宽的带宽内超过了95%.
关键词:
光子晶体波导
脊波导
PWE
FDTD
耦合边界 相似文献
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报道了对高斯型及指数型变耦合系数三波导耦合器的一些重要的全光开关特性进行的研究。利用四阶龙格一库塔方法对指数型和高斯型两类变耦合系数三波导耦合器进行了数值计算。数值计算结果表明:对于变耦合系数三波导耦合器而言,功率可在波导1与波导3之间100%转换,而波导2则不可能达到100%的功率输出。与双波导变耦合系数耦合器相比,在相同的最大耦合系数情况下三波导变耦合系数耦合器开关曲线要更陡一些.即具有更好的开关特性。与平行三波导耦合器相比,变耦合系数三波导耦合器作为光开关的最大优点在于开关曲线中不存在振荡。 相似文献
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以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行以一行耦合介质柱为间距的平行单模线缺陷波导.通过分析和研究光子晶体波导耦合结构的耦合和解耦合特性,发现在不同频率下耦合波导的耦合长度不同.利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合波导的耦合长度,设计了一种新型超微光子晶体波导耦合型三波长功分器,实现了归一化频率分别为0.369、0.394、0.435的光波的分束效果.采用时域有限差分法验证了该功分器具有很好的功率分配效果.本文结果有助于光子晶体新型滤波器、定向耦合器、波分复用器、偏振光分束器以及光开关等光子器件的研究. 相似文献
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用级联缓变结构实现光子晶体波导和传统波导的耦合 总被引:4,自引:4,他引:0
为了提高光子晶体波导与传统介质波导的耦合效率,设计了级联缓变结构.先将传统介质波导中的光耦合进尺寸相当的光子晶体W5波导中,然后W5波导中的光被耦合进尺寸较小些的W3波导中,最后光被耦合进尺寸最小的W1波导.各级波导之间由半径逐渐增大的空气孔连接,空气孔半径逐渐变化相当于波导有效折射率在变化,所以各级波导可以看作是被折射率缓变结构连接起来.由于折射率的缓变,使得光从前一级波导耦合进相邻的后一级波导时反射很小,从而能有效地提高耦合效率.数值计算表明,在光子晶体禁带范围内,除了波导有限长度和波导微小禁带造成的微小不通带外,耦合系数一般能达80%左右,最高可达到95%. 相似文献
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基于不规则波导模式匹配法以及缓变波导中电磁波模式耦合理论,研究了一种W波段圆波导TE62模式激励器. 该波导模式激励器采用矩形波导TE10模式通过侧壁耦合馈入同轴波导,利用同轴波导的选模特性激励TE61模式;随后利用轴向半径周期微扰的圆波导实现TE61–TE62模式变换. 文中推导了矩形-同轴波导模式匹配理论,系统研究了波导结构缓变参数对模式变换效率的影响,完成了模式变换器的优化仿真设计,数值计算结果表明:中心频率处TE62模式的转换效率为94.5%,纯度为98.16%,效率85%以上带宽达到1 GHz,能够满足回旋管冷测的要求.
关键词:
同轴波导
模式变换
耦合模理论
半径微扰 相似文献
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Characteristics of vertical bent coupling between straight and curved rectangular optical waveguides 总被引:3,自引:0,他引:3
In terms of the coupled mode theory (CMT) and the transfer matrix method, we present a technique and relative formulas including the bent coupling coefficient, amplitude coupling ratio, amplitude transmission ratio and propagation power for analyzing the vertical bent coupling between a curved rectangular waveguide and a straight one. Investigations show that the bent coupling appears in an effective coupling region by both sides of the central coupling point. Beyond this effective coupling region, however, the bent coupling is very weak, and the propagation power in the waveguide is closer to a constant. As the bent radius increases, or the thickness of the coupling layer between these two waveguides decreases, this effective coupling region becomes wider, in which the coupling behavior becomes stronger. 相似文献
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用极坐标下的广角光束传播法计算分析弯曲波导 总被引:2,自引:0,他引:2
采用了极坐标下的广角BPM(Beam Propagation Method)对弯曲波导进行了计算模拟,并与极坐标下近轴BPM方法进行了比较,取得很好的结果. 相似文献
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Keh-Yi Lee Chia-Chen Tsai Tsong-Cheng Weng Yi-Lin Kuo Chih-Wei Kao Kuei-Yuan Chen Yu-Jen Lin 《Fiber and Integrated Optics》2006,25(1):29-40
There are several key factors that affect the transmission characteristics of the 90° (L-shaped) bent photonic crystal waveguides. The first factor is the direct coupling efficiency from the incident lights into the waveguides. The second one is the bandgap deviations of the photonic crystals. And the third factor is the optical reflections in the bent corners. In this article, we compare three types of L-shaped bent photonic crystal waveguides. One is the original type, which has an abrupt right-angle bend. Another is an improved 90° bend with a 45°-mirror. The other is an L-shaped bent photonic crystal waveguide with a 45°-transitional section. We investigate their respective frequency responses and observe the improvements in the total transmission efficiencies provided by the latter types. 相似文献
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Jianhua Ji Qian Huang Xuemei Chen Lu Sun Ke Wang Ming Xu Chun Jiang 《Optical and Quantum Electronics》2018,50(6):262
We report the transmission, reflection and loss properties of 90-degree and 135-degree bent silicon waveguide and 90-degree and 135-degree bent surface-plasmon polariton (SPP) waveguides composed of metal thin film and silicon. Finite difference time domain simulation analysis shows that the maximum bending transmittances of 90-degree bent and 135-degree bent silicon waveguides are 51% and smaller than 10%, respectively, and the maximum bending transmittances of 90-degree bent and 135-degree bent SPP waveguides are 80% or so, and they are higher 30% and 70% than that of identically-bent silicon waveguides, respectively. Moreover, the SPP waveguide bend with metal thin film as inner layer of the bend and silicon as outer layer of the bend has much higher transmission than ones with silicon as the inner layer and metal thin film as the outer layer. The waveguide bend with metal as the inner layer and dielectric as the outer layer will be potential for integrated photonic devices and subsystem. 相似文献
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G. Cusmai F. Morichetti P. Rosotti R. Costa A. Melloni 《Optical and Quantum Electronics》2005,37(1-3):343-358
In this work we propose a circuit-based analysis of both a ring phase shifter and a single ring filter, taking into account the effects of imperfections in the directional couplers and polarization conversion in bent waveguides. New models for the directional coupler and for the bent waveguide are proposed and used to find an analytical expression of the transfer functions of ring based devices. The numerical results obtained with the new models show that defects in directional couplers and polarization conversion in bent waveguides are responsible of spectral impairments often observed experimentally, confirming the validity of the model. 相似文献
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By means of the coupled mode theory and transfer matrix technique, a method is presented for analyzing the bending coupling
between straight and bent rectangular waveguides, or between two bent rectangular waveguides. Calculations show that an effective
coupling region exists around the central coupling point, in which the bending coupling appears, beyond which the bending
coupling is very weak, and the propagation power in each waveguide becomes constant. When the bending radius becomes larger
or the central coupling gap becomes smaller, this effective coupling region becomes wider, in which the coupling behavior
becomes stronger. 相似文献
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Hybrid plasmonic waveguides based on a surface oxidized dielectric nanowire placed on a metal surface can facilitate simultaneously deep subwavelength mode confinement and large propagation length. Directional coupling based on such waveguides are theoretically investigated. Much lower crosstalk is noticed for such hybrid plasmonic waveguides compared to conventional waveguides based on bare dielectric nanowires. Some modifications, such as vertically placing the metal surfaces or using a metallic block between the nanowires, are studied which can further reduce the crosstalk between two waveguides. The proposed low crosstalk structures based on hybrid plasmonic waveguides can provide a simple platform for plasmonic integration which can at the same time easily interface with traditional photonic circuits. 相似文献
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Modal conversion between the fundamental mode and the first-order (leaky) mode has been experimentally investigated in high-index-contrast integrated-optical bent waveguides. The matched bend condition has been experimentally confirmed on cascaded bends, and the effect of both matched and unmatched bends on Y branches has been investigated. Good agreement between theoretical predictions and experimental results for both monomode and multimode waveguides is achieved. It is demonstrated that, in bent waveguides, the modal conversion between the fundamental mode and the first (leaky) mode can be accurately controlled to avoid additional losses and transfer function impairments. 相似文献
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采用精确、严格的全矢量模式匹配法,计算了三维脊型弯曲波导和条形弯曲波导的本征模式,分析了模式折射率和辐射损耗随弯曲半径的变化关系.计算结果与已报道的有限差分法的结果符合很好.对文献中已报道但没有深入分析的现象给出了合理的解释.半径为50和12 μm的条形波导的计算结果表明:当波导的弯曲半径减小时,发生在分界面处的TE-TM模耦合会显著增强,这将导致弯曲波导中的模式不再是传统意义上的准TE模和准TM模,而是混合模.随着半径的减小,混合模的横向分量之间的差异会减小,当两个横向分量达到近似相等的强度时,波导的偏振相关性将会大大减小.
关键词:
导波光学
全矢量模式匹配法
微环谐振腔
光波导理论 相似文献