15GHz马赫－陈德尔型Ti：LiNbO_3行波幅度电光调制器

比较了四种马赫－陈德尔调制器的结构特性，表明Ｚ切共面波导（ＣＰＷ）是最好的一种结构。用阶跃倒相电极设计了新型电光光波导幅度调制器，研制了包装式带尾光纤的有５段例相电极的马赫－陈德尔调制器。在１．５３２μｍ波长上，该器件调制带宽为１４．８ＧＨｚ，半波电压为１４Ｖ，消光比为２１．３ｄＢ，光纤－器件－光纤插入损耗７．６ｄＢ。     

高速异型掺杂的硅基槽波导调制器

针对硅基单端推挽调制器的pn结结电容大、调制效率低的问题,设计出一种基于异型掺杂和槽波导结构的硅基调制器。通过槽波导结构和L型掺杂增大了耗尽区与光场相互作用,与传统脊波导相比,在相同调制效率下,槽波导的结电容降低了24%,带宽提高了32%。采用T型轨道的电极实现阻抗和折射率的匹配,4 V偏压下调制带宽达到42 GHz,实现了峰峰值电压V_pp=2 V驱动下70 Gbit/s的OOK信号调制,眼图消光比达5.2 dB。     

超宽带聚合物调制器的优化设计

设计了一种以聚合物作为材料的低损耗、宽带宽的Mach—Zehnder光波导调制器。分析了调制器的脊波导的模式特性,设计了脊波导的结构,并使用BPM软件模拟了脊形波导的光场分布;通过对光场分布的分析,优化了脊形波导的宽度Wg,脊高6,芯层高度H。同时对聚合物调制器的电极进行了优化,包括电极宽度W和电极间距D,使得调制器有较小的导体损耗以及较好的阻抗匹配。并结合了脊波导的结构参数和电极的优化参数,给出了优化结果,它能够使微波的有效折射率与光波的有效折射率达到匹配,从而使带宽达到177GHz,导体损耗为0．2569dB／cm·GHz1／2。     

宽带非均匀半径渐变TE0n-TE0(n+1)模式转换器的设计研究

基于耦合波理论,对两类半径渐变圆波导TE_0n-TE_0(n+1)模式转换器进行理论分析、数值计算和仿真模拟.均匀半径渐变波导高功率模式转换器,采用中心频率为17.14GHz、六周期TE₀₂-TE₀₃模式和中心频率为34.30GHz、六周期TE₀₁-TE₀₂模式两种设计参数.非均匀半径渐变波导高功率模式转换器,采用中心频率为34.30GHz、六周期TE 关键词： 模式转换器 耦合波理论 非均匀半径渐变 转换带宽     

基于有限元法的新结构LiNbO3电光调制器的分析与优化

对传统结构的LiNbO3电光调制器进行了改进,并用有限元法对改进后的电光调制器进行了分析计算,采用T形电极、脊波导和空气背槽的新型LiNbO3电光调制器在进行了结构尺寸优化后,相速完全匹配,带宽可达98 GHz,特性阻抗为52 Ω,损耗系数为0.464 dB/(cm·GHz1/2),半波电压为7.13 V,其性能远优于传统结构的调制器.     

宽带非均匀半径渐变TE0n-TE0(n+1)模式转换器的设计研究

基于耦合波理论,对两类半径渐变圆波导TE0n-TE0(n 1)模式转换器进行理论分析、数值计算和仿真模拟.均匀半径渐变波导高功率模式转换器,采用中心频率为17.14 GHz、六周期TE02-TE03模式和中心频率为34.30 GHz、六周期TE01-TE02模式两种设计参数.非均匀半径渐变波导高功率模式转换器,采用中心频率为34.30 GHz、六周期TE01-TE02模式为设计参数.研究的重点在于保证足够转换带宽的情况下,力求最大化模式转换效率和模式纯度.通过理论分析和模拟,这种新型的非均匀半径渐变波导模式转换器在转换效率和带宽方面都明显优于传统的模式转换器,峰值转换效率达99.5%,转换带宽超过1.5 GHz.     

一种基于光学偏置的新型Math—Zehnder调制器结构设计

设计了一种基于光学偏置并以有机聚合物PMMA／DRI作为光波导材料的新型Mach-Zehdner调制器。利用有效折射率法（EIM）,分析了脊波导的有效折射率随脊波导结构参数变化情况,包括脊宽训、脊高b和芯层厚度d,以及上下包层厚度。采用微带线单电极调制方式结合脊波导的结构设计,实现了微波和光波的速率匹配。针对优化的结构参数,采用BPM方法进行光场和功率传输的模拟仿真,完成了非等臂Math—Zehnder调制器的结构设计,实现了两臂89．84。的初始相位差,消光比约为27dB。     

具有调制功能的多模干涉型1×3分束器

提出了利用量子约束斯塔克(Stark)效应制作具有调制功能的多模干涉型1×3分束器的设计思想,并详细分析了这种光分束器的工作原理。根据理论计算结果,制作了具有调制功能的多模干涉型1×3分束器。分束器的脊型多模波导长度为275μm,宽度为10μm,波导层采用GaAs/AlGaAs多量子阱结构,厚度约为0.2μm;电极采用共面波导结构。首先用有限差分光束传播法模拟了器件的光波传播特性,然后进行了初步的实验验证。理论模拟和实验结果表明,波长为0.86μm的高斯光束对称入射到多模波导的中心,器件实现了3分束功能;施加3 V的直流偏压,器件的调制深度达90%以上、调制带宽为2 GHz,实现了电吸收调制功能。     

InP基矩形马赫-曾德高速电光调制器行波电极设计与测试

提出了一种由新型沟槽耦合器和90°弯曲波导构成的InGaAsP/InP基矩形马赫-曾德电光调制器,对该调制器的L型波导相移臂设计了T型类微带行波电极.首先利用电极的等效电路估算带宽上限,进而在考虑阻抗匹配、回波损耗以及带宽等性能的基础上,使用有限元方法对电极的传输、输入/输出以及过渡区的结构参量进行优化.仿真结果表明由于受到电极输入及过渡区的性能限制,设计的整体行波电极匹配阻抗大于42Ω,回波损耗小于-15dB,带宽可达65GHz.测试制备的Ti/Au行波电极,得到回波损耗为-12dB和带宽为20GHz的最优性能.     

基于PDMS的倒脊形波导电光调制器的设计与制备

选用价格低廉、介电性能良好、低传输损耗的聚二甲基硅氧烷作为波导的包层材料,旁链型分散红1键合聚甲基丙烯酸甲酯作为芯层,设计并制备了一种倒脊形聚合物波导马赫-曾德尔电光调制器及共面波导行波电极,获得了调制器的调制信号响应.针对SF6气体刻蚀聚二甲基硅氧烷的再淀积现象,提出了采用SF6和O2的混合气体对聚二甲基硅氧烷进行反...     

Microwave and millimeter-wave losses in conventional optoelectronic devices

In this paper, microwave characteristics of conventional optoelectronic devices, with emphasis on devices with microstrip (MS) and coplanar waveguide (CPW) electrode structures, are obtained. This analysis is essential for any improvement in the structure of the conventional optoelectronic devices so as to obtain a high performance. Microwave loss is one of the important bandwidth limitation factors in microwave and millimeter-wave (mmW) optical devices. Different sources of loss including ohmic, dielectric and radiating loss in MS and CPW of conventional optical devices are analyzed and compared. The results show that the total microwave loss increases with frequency in conventional MS and CPW waveguides. Also, in traveling-wave optoelectronic devices, the bandwidth is limited in the optical part by effects such as the carrier transit time effect and in the microwave part by factors such as length of the devices in active and non-active sections. In addition, validation of the results in the paper is performed with published theoretical and/or measurement results.     

Optimizing Design for the Traveling Wave Electrodes in Low-Drive High-Speed Electro-Optic Polymer Modulators

Electro-optic (EO) polymer modulators are very promising in the realization of cost-effective and high-performance optical transmissions. In this article, general strategies and specific designs of the traveling wave electrodes in EO polymer modulators were presented to reduce the modulator drive power while maintaining a broadband response. The optimum device parameters and corresponding conditions were estimated using finite element method based on electrode design. In calculating the results, the comprehensive characteristics of polymer modulator with 1.21 V half-wave voltage and 91 GHz bandwidth was demonstrated with electro-optic interaction length is 20 mm, electro-optic coefficient is 55 pm/V, and operation wavelength is 1.319 μm. These results agree with the 0.8 V half-wave voltage and 30 mm electro-optic interaction length reported in Science. In the five designs presented, a hybrid electrode structure combining CPW and microstrip lines were advanced. The characteristics of this structure are like that of microstrip lines with a single-arm electrode on one arm of the waveguide, but it solves the problem of microstrip to coaxial line transition and corona polarization.     

High-Speed Coplanar Waveguide Based Submount for 40 Gbit/s Electroabsorption Modulator

A high-speed submount has been designed and fabricated for 40 Gb/s electroabsorption (EA) modulators. The submount contains a coplanar waveguide (CPW) for microwave signal feeding and a Ta₂N thin-film resistor for impedance matching. The CPW transmission line is designed to ensure low microwave loss and reflection, and Ti/Cu/Ni/Au metal is adopted for electrode fabrication to guarantee good contact with the Ta₂N thin-film. The typical reflection coefficient of fabricated submount is estimated to be lower than−21 dB up to 40 GHz. As a demonstration, a high-speed EA modulator was chip-level packaged using the high-speed submount, and the measured small-signal modulation bandwidth was over 40 GHz.     

Optimizing Design for the Traveling Wave Electrodes in Low-Drive High-Speed Electro-Optic Polymer Modulators

Electro-optic (EO) polymer modulators are very promising in the realization of cost-effective and high-performance optical transmissions. In this article, general strategies and specific designs of the traveling wave electrodes in EO polymer modulators were presented to reduce the modulator drive power while maintaining a broadband response. The optimum device parameters and corresponding conditions were estimated using finite element method based on electrode design. In calculating the results, the comprehensive characteristics of polymer modulator with 1.21 V half-wave voltage and 91 GHz bandwidth was demonstrated with electro-optic interaction length is 20 mm, electro-optic coefficient is 55 pm/V, and operation wavelength is 1.319 μm. These results agree with the 0.8 V half-wave voltage and 30 mm electro-optic interaction length reported in Science. In the five designs presented, a hybrid electrode structure combining CPW and microstrip lines were advanced. The characteristics of this structure are like that of microstrip lines with a single-arm electrode on one arm of the waveguide, but it solves the problem of microstrip to coaxial line transition and corona polarization.     

Sensitivity-bandwidth product for electro-optic modulators

For lumped-element electro-optic modulators, the sensitivity ( partial differentialphi/ partial differentialV) of the phase, phi , in response to an applied voltage V is related to the optical group delay, T(g) , and the bandwidth, Domega . This relationship imposes a fundamental trade-off between the sensitivity and the bandwidth of electro-optic modulators: ( partial differentialphi/ partial differentialV)Domega= (dn/dV)(omega /n) , where n is the optical index. A similar relationship for traveling-wave modulators sets an upper limit on ( partial differentialphi/ partial differentialV) that is proportional to T(g) .     

Refined modeling of traveling-wave Ti:LiNbO3 channel waveguide modulator

A refined computation model for traveling-wave operation of external electro-optical phase modulators made of a single titanium in-diffused lithium niobate channel waveguide (Ti:LiNbO₃WG) is described. The modulator circuit model outlined as two traveling-wave coupled microstrips includes microwave losses and dispersion. In the optimization procedure, we consider different circuit load conditions. The influence of a dielectric overlay covering the electrodes is examined. The consolidated techniques of conformal mapping, multiple image, and finite element are used to investigate the microwave characteristics of the structure, and the refractive effective index method is used in calculating the characteristics of the diffused anisotropic optical channel. The performances of Y-cut and Z-cut substrate configurations are compared. We have verified that the Y-cut substrate modulator gives the best overall performance, and that the overlay presence causes significant improvements in the evaluated modulation efficiency and in the bandwidth. A model of the modulator that takes electrode thickness into account permits one to obtain a wider bandwidth.     

Integration of a Proposed All-Optical Analog-to-Digital Converter using Self-Frequency Shifting in Fiber and a Pulse-Shaping Technique

Integration of a proposed all-optical analog-to-digital (A/D) converter is described. To realize a high-speed and highthroughput system, optical A/D conversion has attracted much attention. A/D conversion generally consists of three processes of sampling, quantization and coding. Whereas an optical sampling technique has already been realized, there have been few investigations on the optical quantization and optical coding technique. We previously proposed an alloptical A/D converter which realizes both optical quantization and optical coding. In this paper, we integrate the proposed all-optical A/D converter to improve its performance and stability. We verify the operation of the integrated all-optical A/D converter composed of a short high nonlinear fiber, arrayed waveguide gratings and variable optical attenuators.     

Design and analysis of coplanar waveguide optical modulator using finite element method

An analysis is given on the finite element method (FEM) for calculating the various parameters of optical modulators and a computer program is written to solve the finite element equation. Based on this method, a Mach-Zehnder type electro-optic modulator with coplanar waveguide (CPW) electrode is designed and fabricated. When compared with the Fourier series method, small differences on the 3-dB bandwidth, characteristic impedance and half-wave voltage, etc. are obtained.     

高动态范围声光接收机

介绍了一种高动态范围声光接收机，这种接收机具备实现宽带射频信号幅度，频率和相位的信道比探测能力，该接收机在０．６３２８μｍ激光器的工作条件下（１．０ｍＷ），声光布拉格盒在５０ｍＷ射频信号区动下，在１４０ＭＨｚ的中心频率上２０ＭＨdisplay status     

Crosstie overlay slow-wave structure for broadbrand traveling-wave type electro-optical modulators

This paper proposes a new crosstie overlay slow-wave structure for a traveling-wave electro-optical modulator and presents a design method including design considerations for the optimum structure. This structure can be designed to satisfy the phase velocity and impedance matching conditions simultaneously over a broad spectral bandwidth. This idea can be applied to a number of electrode structures for broadband traveling-wave optical modulators.