一种新型SOI Mach-Zehnder干涉型电光调制器的设计

在超紧缩双曲锥形3dB多模干涉耦合器的基础上,设计了一种新的Silicon-on-insulator (SOI) Mach-Zehnder干涉型电光调制器.与传统的Y分支器相比,双曲锥形3dB耦合器的制作容差大,而长度缩短了近30%,使得整个器件的尺寸大幅减小.调制区采用横向注入的PIN结构,模拟结果表明:当外加偏压为0.86V时,器件的调制深度最大,此时注入电流为13.2mA,对应的器件功耗为11.4mW.     

基于石墨烯的高效复合波导调制器研究

提出了一种基于石墨烯的复合波导调制器,用严格的三维数值仿真结果展示了该调制器的工作状态。利用调制器狭缝中的表面等离激元对电磁波的强约束,增强了光与石墨烯间的相互作用,提高了调制器的调制性能,调制效率可达0.197dB·μm~(-1)。在调制器长度为15μm时,可实现调制深度为3dB的开关键控效应,此时的插入损耗为0.4dB,调制带宽可达1.85GHz。设计了与输入波导相连接的耦合器,在耦合器总长度仅为1μm的条件下,实现了86.6%的耦合效率。     

S-Band 3dB定向耦合器的优化设计及应用

3dB定向耦合器在组成微波器件中有着广泛的应用, 在我们的实验室中最常用到的带有3dB向耦合器的微波器件是移相器、衰减器和能量倍增器等, 3dB定向耦合器的性能参数对上述器件的性能起着决定性的作用. 在对原有S-band 3dB定向耦合器模拟研究的基础上, 通过对不同组数据的分析比较, 提出了此结构的优化设计方案. 重新设计后的3dB定向耦合器不仅简化了加工工艺, 而且驻波比、不平衡度、隔离度都达到了更好的效果. 将新设计的定向耦合器应用到移相器中, 通过对新老移相器的模拟和测试结果的比较可以看到移相器的各项指标均比原来有所提高, 而这也是以往移相器所无法达到的新指标. 对新加工的移相器试验件的测试数据表明, 实验测试和模拟计算的一致性很好.     

S-Band 3dB定向耦合器的优化设计及应用

3dB定向耦合器在组成微波器件中有着广泛的应用,在我们的实验室中最常用到的带有3dB定向耦合器的微波器件是移相器、衰减器和能量倍增器等,dB定向耦合器的性能参数对上述器件的性能起着决定性的作用.在对原有S-band 3dB定向耦合器模拟研究的基础上,通过对不同组数据的分析比较,提出了此结构的优化设计方案.重新设计后的3dB定向耦合器不仅简化了加工工艺,而且驻波比、不平衡度、隔离度都达到了更好的效果.将新设计的定向耦合器应用到移相器中,通过对新老移相器的模拟和测试结果的比较可以看到移相器的各项指标均比原来有所提高,而这也是以往移相器所无法达到的新指标.对新加工的移相器试验件的测试数据表明,实验测试和模拟计算的一致性很好.     

GaAs2×2Mach-Zehnder光波导开关调制器

报道了GaAs2×2非对称Mach-Zehnder光波导开关调制器的研制结果,分析了这种开关的工作原理和产生串音的因素.采用两个非对称X型耦合器代替传统的Y分支耦合器,得到了性能良好的X型3dB耦合器.λ=1.15μm时,器件的串音比小于-22.4dB,开关电压约1.2V.     

光纤CATV外调制发射机中的复合二次失真及其抑制

复合二次失真(CSO:Composite Second Order Distortion)是光纤CATV中最主要的非线性之一.理论分析表明:在外调制CATV中,将调制器偏置在最佳偏置点可以消除CSO,但外调制器最佳偏置点却随时间及环境温度等漂移,因而会导致CSO的严重恶化.本文提出了一种易于实现的调制器偏置点控制方案,并进行了详细的理论分析与实验研究,结果显示该方案能够将50～550MHz宽频带内电视信号CSO指标抑制在-65dB以下.     

行波电极硅-有机复合集成电光调制器理论分析与实验研究

对基于行波电极的硅-有机复合集成电光调制器进行研究,构建调制器的波导电极结构模型,分析特征阻抗和微波有效折射率对调制器频率响应的影响。通过对电极结构的仿真优化,完成调制器芯片的设计与制备,研究电光聚合物材料的片上极化工艺,得到高性能硅-有机复合集成电光调制器。对研制调制器电极的电学S(Scatter)参数进行测试,分析得到的电极特征阻抗和有效折射率与仿真设计结果基本相符。测试得到电光调制器的3 dB带宽大于50 GHz。     

L波段小型化同轴-共面波导定向耦合器

设计了一种适用于L波段高功率微波辐射场测量的同轴型定向耦合器。分别选择同轴线和金属底板共面波导（CBCPW）作为主副传输线,减小定向耦合器横截面积;利用小孔耦合理论和微元法对耦合结构进行理论分析,选择连续渐变的菱形耦合缝隙,缩短定向耦合器长度;采用数值模拟的方法对耦合器结构进行优化,并对其性能参数进行实验测试,结果表明, 在1~2 GHz频带范围内耦合度约为47 dB,方向性大于17 dB。     

基于最大等增益圆的矢量调制器增益控制方法

矢量调制器因其自身结构小、功耗低等特点已广泛应用于雷达、导航、仪器仪表及卫星通信等领域。基于矢量调制器的最大等增益圆理论,深入分析了增益圆点、半径与调制器增益输出的关系,设计出一种可全频段扫描、一键自动测试的通用矢量调制器增益控制方案,实现了对矢量调制器增益输出以及其平坦度的精确控制,并可灵活设置矢量调制器的精度和平坦度指标,提高了矢量调制器的性能以及校准效率。验证对象为Hittite Microwave公司的HMC1097LP4E矢量调制芯片,单点验证时间不超过1min,增益控制精度可达0.1dB,平坦度可达0.5dB。     

光子集成干涉探测系统关键器件和集成化设计方法研究

基于光波波动效应,采用光束传播法,设计了光程匹配波导、阵列波导光栅、相位调制器以及多模干涉耦合器等光子集成器件。在此基础上,对光子集成器件进行耦合特性分析与计算,设计了完整的光子集成芯片。通过对光子集成干涉系统各组成模块的分析、研究及优化,集成化设计了光子集成干涉探测系统电子样机。结果表明:设计的光子集成器件最小损耗为0.07 dB,光子集成芯片损耗为7.46 dB。光子集成干涉探测系统电子样机在等效口径为110 mm,系统高度口径比为1∶4时,具有视场角0.5°,100 km处空间分辨率5 m的技术指标。     

Study on Control of Bias Point Drifting in Optical Fiber CATV Externally Modulated Transmitters

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Hybrid cable television and orthogonal-frequency-division-multiplexing transport system basing on single wavelength polarization and amplitude remodulation schemes

A hybrid community antenna television (CATV) and orthogonal-frequency-division-multiplexing (OFDM) transport system is proposed and experimentally demonstrated to transmit multiple CATV channels and bi-directional radio frequency signals on a single optical carrier. By polarization remodulating an optical CATV signal with downstream OFDM signals and then amplitude remodulating upstream OFDM signals with the hybrid CATV/OFDM signals, this architecture can efficiently utilize only one optical carrier to support optical analog/digital CATV transmission and bi-directional wireless broadband services for each client. Good experimental results prove that this architecture provides a proper wavelength utilization scheme for future multiwavelength optical transport systems.     

Polarization-modulated analog photonic link with compensation of the dispersion-induced power fading

A novel integrable modulator consisting of a polarization modulator and a polarizer is proposed for constructing a high-performance analog photonic link. By adjusting a polarization controller placed before the modulator, both amplitude modulation and phase modulation with adjustable ratio between them are implemented. This feature is used to shift the peak of the frequency response of a dispersive link to any desired frequency, so the dispersion-induced power fading around the frequency is compensated. A proof-of-concept experiment is performed. The compensation of the dispersion-induced power fading in the proposed analog photonic link increases the spur-free dynamic range as large as 12.5 dB.     

Analysis of dispersion compensation by chirped fiber grating in directly and externally modulated CATV systems

The dispersion compensation effect of the chirped fiber grating (CFG) is analyzed theoretically, and analytic expressions are derived for composite second-order (CSO) distortion in analog modulated sub-carrier multiplexed (AM-SCM) cable television (CATV) systems with externally and directly modulated transmitters. Simulations are given for the two kinds of modulations and for standard single mode fiber and non-zero dispersion shift fiber (NZDSF) systems. The results show that CFG could be used as a dispersion compensator in directly modulated systems, but its dispersion coefficient should be adjusted much more precisely than the externally modulated system. The requirements for the NZDSF system could be loosened much. It is proposed that directly modulated source may be used as a transmitter in CATV systems combined with tunable CFG dispersion compensator being adjusted precisely, which may be more cost-effective than externally modulation technology.     

Optimization of an Externally Modulated RF Photonic Link

The noise figure and sub-octave spurious-free dynamic range of a carrier-suppressed analog RF photonic link are examined. Expressions for noise figure and dynamic range are derived as a function of the modulator bias angle. A closed form expression for the bias angle that optimizes link noise figure and spurious-free dynamic range is also derived. Experimental results are presented and shown to agree with calculations. These experimental results include some of the lowest noise figure and highest dynamic range results published to date for an RF photonic link incorporating a standard Mach-Zehnder modulator: 6 dB and 122 dB·Hz^2/3, respectively.     

Optimization of an Externally Modulated RF Photonic Link

Abstract

The noise figure and sub-octave spurious-free dynamic range of a carrier-suppressed analog RF photonic link are examined. Expressions for noise figure and dynamic range are derived as a function of the modulator bias angle. A closed form expression for the bias angle that optimizes link noise figure and spurious-free dynamic range is also derived. Experimental results are presented and shown to agree with calculations. These experimental results include some of the lowest noise figure and highest dynamic range results published to date for an RF photonic link incorporating a standard Mach-Zehnder modulator: 6 dB and 122 dB·Hz^2/3, respectively.     

一种基于导模共振的电光调制器研究

实验研究了基于导模共振的反射型电光调制器采用的棱镜耦合方式,在棱镜上面镀有4层膜,依次为银膜下电极-极化聚合物-缓冲层-金膜上电极。对这种衰减全反射（ATR）型的聚合物波导电光调制器进行了视频调制实验,采用静态偏置电压稳定模式同步角方法,结合对入射激光束进行监测,解决了视频调制中激光器噪声对模拟信号调制影响的问题,提高了工作稳定性。实验结果表明：该电光调制器具有良好的线性和较高的灵敏度。     

Multiple-Output Fiber-Ring Lasers and Amplifiers in a Hybrid CATV and ADSL Broadcasting Optical Fiber Communication System

In this article we propose two kinds of new fiber ring structure with a semiconductor optical amplifier. The first structure is a one-fiber-ring amplifier with an 8 × 8 fiber coupler and a semiconductor optical amplifier (SOA). The second fiber ring structure is a two-fiber-ring laser including an 8 × 8 fiber coupler, a 2 × 2 E/O modulator, and an SOA. The 14-output spectra of the fiber laser are measured. The gain coefficients of each port of the multiple-output-fiber-ring amplifiers are also measured. We apply these two kinds of fiber ring structures in a hybrid CATV and ADSL broadcasting optical fiber communication system. This application can develop a broadcasting system with large coverage area without using many laser diodes and optical amplifiers. The performance of such a system is also analyzed in this article.     

Multiple-Output Fiber-Ring Lasers and Amplifiers in a Hybrid CATV and ADSL Broadcasting Optical Fiber Communication System

In this article we propose two kinds of new fiber ring structure with a semiconductor optical amplifier. The first structure is a one-fiber-ring amplifier with an 8 × 8 fiber coupler and a semiconductor optical amplifier (SOA). The second fiber ring structure is a two-fiber-ring laser including an 8 × 8 fiber coupler, a 2 × 2 E/O modulator, and an SOA. The 14-output spectra of the fiber laser are measured. The gain coefficients of each port of the multiple-output-fiber-ring amplifiers are also measured. We apply these two kinds of fiber ring structures in a hybrid CATV and ADSL broadcasting optical fiber communication system. This application can develop a broadcasting system with large coverage area without using many laser diodes and optical amplifiers. The performance of such a system is also analyzed in this article.