Manufacture tolerance analysis and control for a polymer-on-silicon Mach-Zehnder-interferometer-based electro-optic switch

To enhance the electro-optic (EO) modulation efficiency and realize the impedance-matching, a polymer-on-silicon multi-mode interference (MMI) Mach-Zehnder interferometer (MZI)-based electro-optic (EO) switch is designed and optimized. Under the central operation wavelength of 1550 nm, the driving voltages of the designed switch are 0 and ±1.375 V, respectively, with a short active region length of 5 mm, and the characteristic impedance of the electrode is about 49.6 ?. The manufacture tolerance is analyzed...     

基于虚拟信号处理平台的差分式中红外甲烷检测系统

利用上位机及Labview工作平台数据处理能力强 的优势,实现了一种针对甲烷(CH₄)气体的双通道差分式中红外检测系统。采用IRGJ型双 通道传感器(英国E2V公司,3.31μm 和3.90μm)检测气体浓度变化,利用Labview和数据采集(DAQ)卡(PCI6221)实现对探测器输出 信号的采集和处理,采用二阶巴特沃斯数字滤波器滤除噪声以提高信噪比(S NR),对系统硬件和软 件进行了集成。系统具有信号采集、滤波、幅值提取、浓度计算、存储及网络发布等功能 。 配备了不同浓度的CH₄气体样品,开展了标定实验,并测量了系统的精度、稳定性和检 测下限等指标。实验结果显示,系统对CH₄气体的测量范围为0~5%,对9种气体样品的 检测误差均小于6%。受传感器自身光程的限制,系统的检测下限约为60×10－6。对浓度为 2000×10－6(0.2%)的气体进行了 长达4h的浓度检测,除个别突变点外 ,检测的最大误差小于10%。由于数据处理能力强,系统功能不受资 源限制并可任意扩展。     

Design and performance of a polymer Mach-Zehnder interferometer electro-optic modulator at 1.55 μm

Based on poled guest-host electro-optic (EO) polymer DR1/SU-8, a Mach-Zehnder interferometer (MZI) EO modulator operated at 1.55 μm is proposed. For achieving high response speed and high EO modulation efficiency, both waveguide structure and electrode structure are especially optimized. The impedance match and less index mismatch are achieved. The final characteristic impedance of electrode is about 49.4 Ω, and the microwave index and the light-wave index are 1.5616 and 1.6006, respectively. The device is fabricated using wet-etching technique and inductively coupled plasma (ICP) etching technique, and its performance is measured at 1.55 μm. Experimental results show that when the applied voltage is tuned, the modulator can be changed from ON state to OFF state. The insertion loss at ON state is 12 dB and the extinction ratio between ON and OFF states is about 10 dB. The high response speed is in nano-second level for a square-wave signal. Therefore, the modulator possesses potential applications in high-speed optical networks on chip.     

Design and implementation of differential mid-infrared carbon monoxide detector

Based on wide-band infrared(IR) light source and dual-channel pyroelectric detector with detection channel of 4.66 μm and reference channel of 3.95 μm,a differential mid-infrared(MIR) carbon monoxide(CO) detector is designed and implemented.In order to reduce the detection limit and improve the detection sensitivity,an open spherical mirror chamber is designed and fabricated according to the divergence angle of the light source.The CO detection system is established using the welded and debugged detection circuits,a series of CO gases with different concentrations are prepared,and gas concentration calibration experiment is carried out.Experimental results indicate that after the amplifying circuit,the signal-to-noise ratios(SNRs) of the two channels are 17.58 dB and 18.46 dB,respectively,and the detection error of this system is less than 9% in 0%-4% measuring range.The detection sensitivity in the low concentration range is approximately 0.05%.6 h measurement on the 0 ppm sample gas shows that the fluctuation range is about ±0.02%,and the measurement standard deviation is about 0.89%.     

An ultra-compact cross/bar optical routing switch using two polymer electro-optic microrings

A 2×2 cross/bar polymer electro-optic(EO) routing switch is proposed,which is composed of two passive channel waveguides and two active EO polymer microrings with bending radius of only 13.76 μm.Detailed structure,theory and formulation are provided to characterize the output power of the switch.For obtaining fundamental mode propagation,small bending loss and phase-matching between channel waveguide and microring resonator(MRR) waveguide,the structural parameters are optimized under the wavelength of 1550 nm.Analyses and simulations on output power and output spectra indicate that a switching voltage of 5 V is desired to realize the exchange between cross state and bar state,the crosstalk under cross state and that under bar state are about 28.8 dB and 39.9 dB,respectively,and the insertion losses under these two states are about 2.42 dB and 0.13 dB,respectively.Compared with our four EO switches reported before,this device possesses ultra-compact size of 0.233 mm×0.233 mm as well as low crosstalk and insertion loss,and therefore it can serve as a good candidate for constructing large-scale optical routers or switching arrays in photonic network-on-chip(NoC).     

基于AgGPS的自动变量施肥控制系统研究

该设计是以卫星精确定位系统AgGPS以及传感技术为基础的自动变量施肥控制系统,其目的是实现对施肥量的精确控制.工业控制机依据直接从AgGPS接收机中读取施肥机机具的位置、速度数据或者间接由传感器读入脉冲数据再将其转换为机具速度,并结合施肥量网格数据库处理后产生控制信号,使CPLD控制模块输出一定频率的步进电机驱动脉冲,控制排肥轴转速大小,从而对施肥量进行控制,以实现资源的优化配置.     

一种嵌入式中红外甲烷检测系统的研制

为了实现检测系统的便携化、小型化和较强的数 据处理能力,结合ARM 11嵌入式处理器和 LabVIEW数据处理平台,设计并实现了一种嵌入式中红外差分甲烷检测系统。在软件方面, 选用S3C6410 作为主处理器、WinCE作为嵌入式操作系统,采用Platform Builder工具对该系统的内核文 件进行裁剪定 制以及移植安装;采用具有较强数据处理能力的LabVIEW作为数据处理平台,通过Touch Pan el模块编写 并生成可直接运行于WinCE系统的应用程序来处理传感信号。在硬件方面,选用双通道集成 传感器IR12GJ, 其输出的两路传感信号经前端电路放大和滤波处理后,由数据采集卡对其进行采集并传输给 LabVIEW软 件程序,经数据处理后获得甲烷浓度。基于所集成的系统,开展了气体标定、误差测量以及 系统稳定性实 验。实验结果显示,本系统对甲烷气体浓度的检测范围为0~6.5%,对 12种气体样品的相对检测误差小于 10%。对浓度为0.5%的气体样品进行了长达4小 时的稳定性检测,除个别突变点外,最大误差为8.3%。本 文所设计的检测系统结合了嵌入式系统体积小以及LabVIEW数据处理能力强的优点,从而具 有较好的应用前景。     

CO and CO2 dual-gas detection based on mid-infrared wideband absorption spectroscopy

A dual-gas sensor system is developed for CO and CO2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing (TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million (ppm) in volume and 2.6 ppm for CO and CO2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO2, respectively. The reported sensor has potential applications in various fields requiring CO and CO2 detection such as in the coal mine.     

“信号与系统”课程思政的教学探索

为培养德才兼备的全方位人才,在“信号与系统”课程中融入课程思政,努力实现知识传授、能力提升、价值引领的融合统一。从课程知识点、敏感话题、杰出人物、实验实践等多角度深入挖掘“信号与系统”思政元素,并在课程中践行思政,在完成知识目标和技能目标的同时,培养学生的人生观、价值观、家国情怀及使命担当。     

聚合物脊形波导定向耦合电光开关的电极优化

给出了一种新型聚合物脊形波导定向耦合电光开关的结构模型和设计方法.应用保角变换法和镜像法分析了对称共面双电极的电场分布.为了获得最小的模式损耗和开关电压,优化了电极厚度、电极宽度和电极间距.为了使器件实现正常的开关功能,讨论了所能允许的开关电压的波动范围.模拟计算结果如下:脊形波导的芯宽度4.0μm,芯厚度1.5μm,脊高0.5 μm,耦合间距3.0μm,优化后的电极厚度0.15 μm,电极宽度3.0μm,电极间距3.5μm,耦合长度3 082μm,开关电压5.43 V;当开关电压在5.28到5.59 V范围内波动时,器件的插入损耗小于0.60 dB,串扰小于-30 dB.与BPM仿真结果的对比表明,该优化方法具有较高的精度.