光子晶体波导耦合的波分复用研究

两平行光子晶体单模波导的相互耦合组成一个耦合结构。两本征模的色散曲线相交并出现简并,简并模之间的耦合作用使模式的分布发生了改变。由于耦合的作用,各个波长的光波会在不同的波导中传输。在简并点处两本征模发生解耦合,光波会沿着原来的方向传输。将两个不同耦合长度的光子晶体波导耦合结构集成在一起,就可以组成一个三波长的光子晶体波分复用器。     

平行光子晶体波导的传输特性及应用

采用时域有限差分法研究两平行光子晶体波导的传输特性及模场分布,利用耦合模理论计算光子晶体波导的耦合系数。计算结果表明,在不同的频率范围内两平行光子晶体波导之间表现出不同的耦合特性:在高频段(0.32~0.44)(ωa/2πc)的范围内两直波导表现出相互的能量交换,实现光耦合,耦合系数随入射波 频率增加而减小;而在低频段(0.29~0.32)(ωa/2πc)的范围内,两波导的传输谱图几乎重合。最后,提出一种采用固定波导耦合长度同时实现光分束及光均分器的方案,当耦合长度取34a时,可将频率为0.333 (ωa/2πc)和 0.357(ωa/2πc)的两入射波分束传播,同时将低频段中的任意频率波进行能量均分。     

基于绝缘体上的硅材料的全内反射型阵列波导光栅器件的设计

设计了一种基于绝缘体上的硅材料的全内反射型阵列波导光栅解复用器年。将一全内反射波导镜引入原弯曲的波导列阵中，该波导镜具有偏振补偿的功能和缩小器件尺寸的特点。在器年数值模拟的基础上，制作了原理性器件，并获得了初步的实验结果。     

Wavelength Demultiplexing Structure Based on Coupled-Cavity Waveguides in Photonic Crystals

A structure based on photonic crystals for optical wavelength demultiplexing is proposed and analyzed. This structure consists of two coupled-cavity waveguides, each one tuned at a different frequency transmission band. A model based on the tight-binding method taken from solid-state physics is used to design the working frequencies of the waveguides. The demultiplexing behavior is demonstrated by means of simulations employing a finite-difference time-domain method. It is concluded that the demultiplexing mechanism presented here may be used as a building block in multifunctional lightwave integrated circuits based on photonic crystals.     

Transmission Characteristics of 90° Bent Photonic Crystal Waveguides

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.     

二维三角晶格光子晶体波导的辐射特性

利用二维三角晶格光子晶体,设计了一种能够提高波导辐射效率的光子晶体结构。通过在单波导出口端级联一耦合波导列的方式形成一种复合式结构,利用时域有限差分法研究了该结构的光辐射特性。结果表明,采用级联波导列的结构能有效提高光辐射效率。进一步对器件进行了优化,使级联波导列与单波导之间的距离为1.8a,波导列横向和纵向的周期数分别为6和5,辐射效率可达到最大值,在辐射距离为100a处,辐射功率可达到20%以上。该类型光子晶体器件在近场光学和集成光学等方面有潜在的应用价值。     

光子晶体光纤超平坦色散特性的研究

利用有效折射率方法的标量近似理论对三角排列的光子晶体光纤超平坦色散特性进行了理论分析和数值模拟,研究发现改变光子晶体光纤包层空气孔半径或空气孔间距可以改变波导色散的特性,从而可以设计在不同波段,不同大小值的超平坦色散。本文的计算和分析可以为设计不同色散特性的光子晶体光纤提供理论依据。     

跑道型结构光子晶体波导定向耦合器

鉴于波导定向耦合器在集成光路以及光电集成方面的广泛应用,提出了一种基于光子晶体波导间高效耦合的光子晶体定向耦合器。通过主波导和耦合波导间的耦合,可以实现对波长为1 490 nm和1 550 nm电磁波的高效分光。在将器件长度控制在30 μm左右的同时,其总效率高达93.05%。另外,发现主波导和耦合波导间介质柱结构参数对电磁波的耦合周期有着极大的影响。并通过将介质柱沿z方向拉伸0.1a(a为晶格周期),设计了工作波长为1 530 nm和1 540 nm的光子晶体定向耦合器,器件长度仅为60 μm。通过拉伸介质柱的纵向长度,可以大幅减小耦合周期,这对缩小器件体积以及实现更为密集的波分复用有着重要的意义。     

Investigation of Infrared Photonic Crystal Slab with Defect Waveguides

This paper deals with the two dimensional (2-D) infrared photonic crystal slab with an air-bridge structure featuring defect waveguides in which the optical propagation properties were obtained by measurements of transmission spectra. 3-D finite-difference time-domain (FDTD) simulations have revealed the appearance of four defect propagation modes for the band structure and transmission spectra in the air-bridge slab. These defect modes were experimentally identified in the measured transmission spectra.     

光子晶体耦合波导实现光开关效应的研究

提出了一种基于光子晶体耦合波导实现光开关效应的方法:将线缺陷引入二维光子晶体以形成两平行的邻近波导,两邻近波导及其中间的两排介质柱构成了光开关模型耦合区;利用平面波展开法计算了不同介质填充率情况下的色散特性.结果发现:减小介质填充率可以实现波导耦合长度的减小;分段调整中间介质柱的填充率和选择不同的耦合搭配长度,定向耦合...     

Proposal for a New Dense Wavelength Division Multiplexing Filter Based on Two-Dimensional Photonic Crystal Ring Resonator

Abstract

A new optical filter design based on a two-dimensional photonic crystal ring resonator structure with an N-channel model is proposed in this article. This study also shows that modifying the scatter radius and the waveguide width can significantly improve the performance of the original structure, which can solve the mode mismatch problem for output waveguide. Here, an example of a 16-channel photonic crystal ring resonator is provided; wavelength spacing of 1.6 nm and a high quality factor Q of 6,000 were achieved. The optical filter would be a potential key component in the application of dense wavelength division multiplexer devices.     

阵列波导光栅线性系统理论分析及优化设计

运用线性系统理论分析了阵列波导光栅的模场特性 ,导出器件传输的数学模型即光栅方程。提出了设计阵列波导光栅阵列波导数M的新方法 ,该方法综合考虑了降低器件串扰以及收集发散光场的能力 ,与文献 [1 ]的方法相比简单且准确。分析了造成器件衍射损耗的原因 ,提出了降低器件衍射损耗的方法。给出了 8× 0 .8nm ,中心波长为 1 550nm的阵列波导光栅波分复用器的设计实例 ,并进行了数值模拟计算验证了文中所提方法的准确性。     

Numerical Analysis of Coupling between Two-Dimensional Conventional Dielectric Waveguides and Photonic Crystal Waveguide

A problem of coupling between conventional dielectric waveguides and a two-dimensional photonic crystal waveguide is analyzed, using the Fourier series expansion method combined with the absorbing boundary condition of a perfectly matched layer (PML). A novel structure for the input and output ends of the photonic crystal waveguide is proposed to increase the coupling efficiency. Numerical examples are demonstrated and discussed to validate the effectiveness of the proposed structure.     

Photonic Integrated Circuits for Cost-Effective,High Port Density,and Higher Capacity Optical Communications Systems

Abstract

Bandwidth-hungry services, such as higher speed Internet, voice over IP (VoIP), and IPTV, allow people to exchange and store huge amounts of data among worldwide locations. In the age of global communications, domestic users, companies, and organizations around the world generate new contents making bandwidth needs grow exponentially, along with the need for new services. These bandwidth and connectivity demands represent a concern for operators who require innovative technologies to be ready for scaling. To respond efficiently to these demands, Alcatel-Lucent is fast moving toward photonic integration circuits technologies as the key to address best performances at the lowest “bit per second” cost. This article describes Alcatel-Lucent's contribution in strategic directions or achievements, as well as possible new developments.     

光子晶体表面光波导的特性研究

采用平面波展开法和时域有限差分法,研究了光子晶体表面光波导的色散及光传输特性。研究结果表明,表面模的出现及其色散特性与表面介质柱的半径相关,色散曲线的斜率保持单调变化,并在最低或最高频率附近展现低群速度频率区。由于光子带隙和全内反射的共同影响,光场将沿晶体表面高效率地传输。研究结果为探索在光子晶体外部控制光传输具有重要的理论意义。     

光子晶体环形谐振腔异质结构超微多路光分束器

基于直波导和环形谐振腔的耦合特性,设计了一种新型、高效的二维光子晶体异质结构光分束器.时域有限差分法模拟表明,该设计仅仅通过改变介质柱的折射率,使光场发生重新分布,便可实现输出能量的均分或自由分配.在通信波长范围,该设计结构尺寸小、分束角度大、分束率高,这些特性使其在光通信领域具有重要的应用前景.     

柚子型光子晶体光纤啁啾光栅的反射谱特性

利用有限元法和传输矩阵法,对柚子型结构的光子晶体光纤啁啾光栅的反射谱进行了理论分析。得到了啁啾光栅参数和光纤参数对光子晶体光纤啁啾光栅反射谱的影响规律。结果表明随着啁啾系数和折变量的增加,光栅反射谱呈规律变化,当啁啾系数增大到一定程度时几个反射峰会连到一起,形成一个大的反射带宽。光纤的内包层直径和纤芯直径的改变能够影响各反射峰之间的间距。同时研究了切趾变迹对光子晶体光纤啁啾光栅反射谱的影响,研究表明,所用切趾函数会同时对多个峰进行切趾,每个峰的切趾效果都很好。对反射谱波动较大的几个峰相连的啁啾光栅经过柯西切趾后反射谱曲线平滑,适合于实际应用。     

光子晶体光纤的基模分析

简化了光子晶体光纤的模式计算公式，计算了六角晶格光子晶体光纤的色散关系，对不同空气柱半径的色散作了比较，发现随着空气柱半径的增加，模式折射率变小，波导模式色散的零色散点向长波方向移动。     

非线性一维光子晶体波导光双稳

利用非线性折射率系数较大且非线性时间响应较快的CdS_xSe_1-x玻璃为材料,设计并制备了非线性一维光子晶体波导光双稳器件,该器件的折射率空间分布呈正弦形式。实验测得双稳开关的阈值功率密度为1.60×10⁵W/cm²,开关时间为63ps。采用时域有限差分方法讨论了光子晶体带隙随入射光强变化而移动的情况,随着入射光功率密度的增加,光子晶体的带隙中心向短波方向移动。同时计算了该器件的双稳特性,理论计算得到双稳开关的阈值功率密度为1.40×10⁵W/cm²,开关时间约为50ps。获得了理论与实验基本一致的结果。     

光子晶体光纤的色散特性及其应用

光子晶体光纤(PCF)的色散特性与传统光纤有显著的差别。从光子晶体光纤的结构特点出发，分析了PCF的色散特性，介绍了其潜在应用。