仅有相邻波导耦合的定向耦合器的一般解法

应用切比雪夫多项式 ,求得了仅有相邻波导耦合的 (N +1)× (N +1)定向耦合器在弱耦合、无损耗和忽略正交偏振模场分量间耦合的情形下波导耦合方程的通解。列出线形排列 2× 2 ,3× 3,4× 4定向耦合器的解的表达式 ,并对环形排列 3× 3定向耦合器的解作了较详细的分析     

多波导定向耦合器耦合特性

利用拉普拉斯变换,将多波导定向耦合器的耦合模方程组变换为三对角线性方程组,并采用追赶法求出了该方程组的通解;进一步,给定初始条件,进行拉普拉斯变换反演,即可严格地求出该耦合模方程组的解。采用该方法研究了5波导定向耦合器光从一个波导入射和等光强从5个波导入射时的耦合特性,求出了耦合模方程组解的解析表达式,给出了每个波导中光功率变化规律曲线。利用该方法,可很方便地求出任意有限数目波导组成的定向耦合器在任意入射条件下耦合模方程组的解,因此对于多波导定向耦合器结构的合理设计,具有非常重要的意义。     

高功率千瓦级(N+1)×1光纤级联泵浦耦合器

分析了泵浦光纤不同锥区长度对(1+1)×1耦合器效率的影响,相同锥区长度不同泵浦臂数量对(1+1)×1耦合器与(2+1)×1耦合器效率的影响,结果表明泵浦光纤锥型区域越长,通过泵浦光纤进入信号光纤的泵浦光越多,泵浦耦合器的耦合效率越高和相同锥区长度下,泵浦臂数量越多,泵浦耦合器耦合效率越低.根据分析结果制作了(1+1)×1耦合器与(2+1)×1耦合器,通过两个(N+1)×1耦合器级联方式形成级联泵浦耦合器.测试了由两个(1+1)×1耦合器组成的级联泵浦耦合器,在总注入泵浦功率602W的情况下输出泵浦功率564W,级联泵浦耦合效率高达93.6%.由两个(2+1)×1耦合器组成的级联泵浦耦合器,在总注入泵浦功率1 210 W的情况下输出泵浦功率1 120 W,级联泵浦耦合效率高达92.5%,实现了千瓦级泵浦功率输出,且两种级联泵浦耦合器信号光损耗均小于0.4%.利用此方法将耦合器形成级联结构可有效提高光纤激光器系统泵浦输出能力,实现千瓦级高功率输出.     

跑道形玻璃波导谐振腔滤波器的研制

采用Ag+-Na+离子工艺,在K9玻璃上制备了跑道形波导谐振腔滤波器.测试得到该滤波器自由光谱范围为FSR=0.177 nm,对比对为Cr＝7.5 dB.同时分析得到耦合器的耦合系数为κ=0.916,耦合器和环形腔的损耗因子分别为δ=0.55,γ=0.48.耦合器的两波导几乎相连、条波导边缘不规则和一次离子交换波导表面缺陷是造成该波导滤波器具有较大损耗的主要原因.通过改进工艺技术降低波导损耗,该滤波器可以用于光通信、传感等领域,也可与其它波导结构相结合实现新的功能.     

平面弯曲波导耦合器的特性分析

根据耦合模理论和弯曲波导耦合器的结构特点,对平面弯曲波导耦合器的特性进行了分析,结果表明弯曲波导耦合器的弯曲半径和最小间距两个可调变量,增加了波导器件设计的灵活性;同时由于等效耦合长度的调制作用使得弯曲波导耦合器在波分复用/解复用中比平行直波导耦合器具有更大的复用带宽;分析了弯曲半径和最小间距对弯曲波导耦合器复用带宽的影响,为实际波导器件的设计制作提供了一定的理论依据.     

氮化硅片上光栅耦合器的优化和实验

在785 nm激励的拉曼片上传感器结构中，氮化硅片上光栅耦合器的性能直接关系到激励光的耦合效果。首先建立了光栅耦合器的二维、三维结构模型，采用时域有限差分（FDTD）仿真软件对光栅耦合器进行数值分析。以耦合效率为主要性能指标，分析了光源入射角度、光栅常数、光栅高度、填充因子和光栅刻蚀深度各参数的影响。采用电子束光刻法制备了光栅耦合器。最后，对三维全刻蚀聚焦波导光栅耦合器进行了测试。结果表明，二维波导光栅耦合器的性能最好，其耦合效率可达39.64%，三维全刻蚀聚焦波导光栅耦合器在实际测试中的耦合效率能达19.91%。光栅耦合器能有效将光耦合进波导中，在波导传感中具有潜在的应用。     

棱镜-漏波导耦合器的理论分析

根据多光束干涉原理,理论上分析了棱镜-漏波导耦合器,且与棱镜-波导耦合器作了比较,给出正确使用这两种耦合器的判据.分析结果表明,在强耦合条件下,棱镜-漏波导耦合器可用于薄膜参数测量和光波导输入-输出耦合;对于弱耦合,本文的结果与Tien和Ulrich的理论一致.     

变耦合系数非线性三波导定向耦合器特性研究

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。     

基于LiNbO_3的长周期波导光栅可调谐耦合器的设计

设计了一种基于LiNbO_3的长周期波导光栅可调谐耦合器.该耦合器利用长周期光栅的独有特性将输入波导的导模经包层模耦合至输出波导导模.由于LiNbO_3的电光效应,波导光栅芯层与包层的有效折射率随外加电压变化,从而耦合器的谐振波长及耦合效率可由外加电压调谐.分析了光栅周期与耦合器的长度对耦合器带宽和耦合效率调谐范围的影响,以及波导尺寸对谐振波长调谐灵敏度的影响.结果表明光栅周期越短,耦合器长度越长,则耦合器的带宽越窄,耦合效率调谐范围也越大.此外,谐振波长调谐灵敏度随波导宽度的增加而减小,而波导厚度对谐振波长调谐灵敏度的影响可以忽略.对光栅周期为94μm、长度为3.52cm的耦合器进行仿真,结果表明,谐振波长灵敏度为26.2pm/V,3dB带宽可达4.5nm,当外加电压从0变化到200V时,谐振波长变化5.24nm,耦合效率可在1到0.15之间进行调谐.     

光纤通信光开关的物理基础(续)

3.2　定向耦合器电光开关定向耦合器电光开关是在电光材料 (如L i Nb O3、化合物半导体、有机聚合物 )的衬底上制作 1对条形波导和 1对电极构成 ,如图 5所示 .当不加电压时 ,它是 1个具有 2条波导和 4个端口的定向耦合器 .一般称 1 -3和 2 -4为直通臂 ,1 -4和 2 -3为交叉臂 .图 5　定向耦合器型光开关假设两波导的耦合较弱 ,各自保持独立存在时的场分布和传输系数 ,耦合的影响只表现在场的振幅随耦合长度的变化 .设两波导中的复数振幅分别为 E1(z)和 E2 (z) ,相位常量是β1和 β2 ,其变化规律可用一阶微分方程组表示 [3]d E1(z)dz =-ik12…     

1×7锥形混合棒塑料光纤耦合器

利用光线追迹法进行数值仿真得到了锥形混合棒塑料光纤耦合器的分光比与其长度的关系.数值仿真表明:这种耦合器的分光比随锥形光波导长度增加,在0.143(即均分处)上下呈振荡型变化.选择一均分且分光比变化平缓的区域作为制作光波导的长度,通过拉伸粗的光波导棒成锥形且达到所需的长度,并采用精密的机械连接,制作出了1×7塑料光纤耦合器.测试数据表明:这种塑料光纤耦合器具有很高的均匀性.     

光通信中的玻璃无源器件的制备与研究

本文报道了以高质量的BK7光学玻璃为衬底,通过稀释Ag+-Na+离子交换技术,制备出低损耗的表面条波导,并用近场法测量出条波导的模场分布曲线。给出光纤与波导耦合的失配损耗为0.54dB,条波导传输损耗为0.21dB/cm.以及在此工作基础上,成功地研制了适用于大容量相于光通信系统的1×2和1×4单模波导分束器。     

ON THE APPLICATION OF A GENERALIZED VERSION OF THE DRESSING METHOD TO THE INTEGRATION OF VARIABLE COEFFICIENT N-COUPLED NONLINEAR SCHRÖDINGER EQUATION

N-coupled nonlinear Schrödinger (NLS) equations have been proposed to describe N-pulse simultaneous propagation in optical fibers. When the fiber is nonuniform, N-coupled variable-coefficient NLS equations can arise. In this paper, a family of N-coupled integrable variable-coefficient NLS equations are studied by using a generalized version of the dressing method. We first extend the dressing method to the versions with (N + 1) × (N + 1) operators and (2N + 1) × (2N + 1) operators. Then, we obtain three types of N-coupled variable-coefficient equations (N-coupled NLS equations, N-coupled Hirota equations and N-coupled high-order NLS equations). Then, the compatibility conditions are given, which insure that these equations are integrable. Finally, the explicit solutions of the new integrable equations are obtained.     

多模干涉马赫曾德尔光开关模型

根据N×N多模干涉耦合器的基本原理 ,确定了多模干涉耦合器的结构参数。通过分析多模干涉耦合器的输入光场与其映像间的相位关系 ,提出了模传输矩阵的分析方法 ,并用此方法分析了N×N普通干涉多模干涉耦合器、N×N相移器以及N×N普通干涉多模干涉马赫 曾德尔光开关 ,得到了它们的模场传输方程 ,分析了光开关在光场从任一输入端输入 ,从任一输出端输出时开关的驱动条件。用上面的方法分析了 4× 4光开关的结构及驱动条件     

Optical properties of He+-implanted and diamond blade-diced terbium gallium garnet crystal planar and ridge waveguides

Terbium gallium garnet (Tb₃Ga₅O₁₂, TGG) crystal can be used to fabricate various magneto-optical devices due to its optimal Faraday effect. In this work, 400-keV He⁺ ions with a fluence of 6.0×10¹⁶ ions/cm² are irradiated into the TGG crystal for the planar waveguide formation. The precise diamond blade dicing with a rotation speed of 2×10⁴ rpm and a cutting velocity of 0.1 mm/s is performed on the He⁺-implanted TGG planar waveguide for the ridge structure. The dark-mode spectrum of the He⁺-implanted TGG planar waveguide is measured by the prism-coupling method, thereby obtaining the relationship between the reflected light intensity and the effective refractive index. The refractive index profile of the planar waveguide is reconstructed by the reflectivity calculation method. The near-field light intensity distribution of the planar waveguide and the ridge waveguide are recorded by the end-face coupling method. The He⁺-implanted and diamond blade-diced TGG crystal planar and ridge waveguides are promising candidates for integrated magneto-optical devices.     

K+-Na+和Ag+-Na+两步离子交换技术制作玻璃基光波导研究

利用K+-Na+和Ag+-Na+两步离子交换得到掩埋型光波导.该方法抑制Ag+-Na+离子交换时产生的Ag+微粒,降低波导损耗,增加波导截面的圆对称性,从而提高光波导器件的性能.用该方法制作了1×8光功分器,其插入损耗平均为10.9 dB.     

3-D Electromagnetic Modeling of Polarization-Dependent Coupling Characteristics of 1×3 Linear Array Weakly Fused Fiber Couplers

Based on the full-wave surface integral equations method and the steplike approximation technique, a three-dimensional (3-D) electromagnetic model for simulating polarization-dependent power-coupling behavior of 1×3 linear array weakly fused fiber couplers is proposed. The accuracy of the proposed numerical model is confirmed to be good by comparing with the measured power transfer behavior at the fusing and elongating process of the couplers. In the 3-D modeling view, the polarization-dependent coupling behavior of two practical couplers, 1/3 power splitter and wavelength-flattened coupler, are numerically studied. It is seen that as the coupler is designed in a very weakly fused condition the polarization-dependent loss (PDL) is significantly increased. For designing the 1×3 coupler with low PDL, it is suggested that the aspect ratio has to be controlled in stronger fused range between 0.8 and 0.9.     

4 × 4 Plastic Optical Fiber Star Coupler Incorporated with a Common Polymer Waveguide Optical Power Distribution Region

Abstract

Two types of 4 × 4 plastic optical fiber star couplers incorporated with a polymer waveguide as the optical power distributor are proposed, and their high performances are demonstrated. The characteristics of the proposed star coupler are investigated based on ray optics, and its power distribution performance is evaluated in terms of the flatness of the coupling ratio and the amount of the excess loss. Under the best conditions, the flatness of the coupling ratio and the excess loss of the fabricated device have been obtained as 2.0 dB and 2.5 dB, respectively.     

Optical Code Generating Device Using 1×N Asymmetric Hollow Waveguide Couplers

An optical code generating device for security access system application is presented. The code generating device constructed using asymmetric hollow optical waveguide coupler design provides a unique series of output light intensities which are successively used as an optical code. The design of the waveguide is made using two major components which are asymmetric Yjunction splitter and a linear taper. Waveguiding is done using a hollow waveguide structure. Construction of higher level 1×N hollow waveguide coupler is done utilizing a basic 1×2 asymmetric waveguide coupler design together with a cascaded design scheme. Nonsequential ray tracing of the asymmetric hollow optical waveguide couplers is performed to predict the optical transmission properties of the waveguide. A representation of the code combination that can be generated from the device is obtained using combinatory number theory.     

Single and multi-section CTL and branch-line CPW directional couplers with broadband performances for SIMMWIC

Single and multisection branch-line and coupled transmission line (CTL) directional couplers have been implemented in coplanar waveguide (CPW)-technology, showing broadband performances. The branch-line and CTL couplers had a phase balance of ±5° and a power variation of 1.5 dB in the coupling over a bandwidth of greater than 25% and 75% respectively. The experimental values for the couplers were found to agree well with simulated results. The CPW couplers provide larger bandwidth than comparable microstrip couplers. Investigation on different feeding structure for the branch-line couplers is also presented.