PC-compatible optical data acquisition unit

A personal computer compatible optical data acquisition unit is described. The unit hardware architecture consists of optical analog sensors, optical digital sensors, and standard digital-to-analog converters. It can be accessed and programmed using a variety of programming languages. The unit has several applications in color sorting, data communication, aerospace guidance, and remote optical sensing.     

基于FPGA 的超导动态电感探测器频梳读出信号产生

超导动态电感探测器(Kinetic Inductance Detectors, KIDs) 作为一种新型的超导探测器, 在天文学等领域得到了广泛应用, 具有高灵敏度、 高能量分辨率等优点, 并且可以通过频域复用直接扩展到大型阵列. 然而, 为了支持上千像素的探测,KIDs 阵列需要产生复杂的频梳信号, 占用较大的信号带宽. 因此, 数模转换器件(Digital-to Analog Converter, DAC) 的采样率对于 KIDs 阵列的读出电路实现至关重要. 基于JESD204B 传输协议的高速 DAC相较于传统低电压差分信号(Low-Voltage Differential Signaling, LVDS) 协议的转换器具有更高的采样率和传输速率, 可用于频梳信号波形的产生. 为此, 本文提出了一种基于现场可编程门阵列(Field Programmable Gate Array, FPGA) 的设计, 以 Xilinx 公司 Kintex-7 系列 FPGA 为主控芯片, 通过高速串行接口JESD204B 和高速 DAC 芯片AD9136 实现高速数据传输,DAC 采样率为2 GSPS, 能生成带宽为1 GHz 的基带信号. 实验结果表明, 该设计能够有效地生成复杂的频梳信号, 具有较高的信号质量和灵活性, 解决了传统 DAC 及直接数字频率合成(Direct Digital Synthesizer, DDS) 器件难以产生复杂多变波形的难题, 有助于拓展 KIDs 阵列的工程应用.     

Design optimization for microwave coupling structures of a digital-to-analog converter based on series arrays of high-temperature superconducting Josephson junctions

A new coupling scheme of the external microwave signal for a digital-to-analog converter based on series arrays of high-temperature superconducting Josephson junctions has been proposed. It is suggested to couple the meander-like array inductively to a parallel microwave transmission line. Within the resistively shunted junction model different types of microwave coupling structures were analyzed with the goal to reduce the mutual phase locking and to achieve high output power and phase-locking stability. A harmonic balance technique was used to derive an analytic expression connecting the amplitudes of microwave voltages and currents in the array and the frequency of the external signal. Numerical simulations were performed to determine the boundaries of stable locking as a function of circuit parameters.     

Experiment on constructing and studying a combined sensor array

The paper presents the results of studying a breadboard model of a vector combined hydroacoustic array created in the mid-1980s. The combined sensor array was developed on the basis of molecular-electronic hydroacoustic pressure-gradient sensors. According to the experimental data, the gain from joint processing of the total pressure and pressure-gradient channels exceeded 20 dB. The paper discusses the parameters of molecular-electronic converters, which ensured the qualitative characteristics of the combined array.     

Analog light signal based opto-electronic ring-oscillator and tunable oscillation frequency

This paper demonstrates opto-electronic ring-oscillator constructed by an odd number of opto-electronic inverters for the digital (electric) and analog (light) signals based on mixed-signal communications. The opto-electronic inverter is consisting of light-emitting and light-receiving parts which can be regarded as a digital-to-analog and an analog-to-digital converters, respectively. To investigate the light-signal processing properties, the oscillation frequency (f_osc) studies were performed by controlling three different parameters of load resistors (R_L), light wavelengths (λ), and photosensor type. The smaller R_L or the shorter λ of the light signal brings the faster f_osc in opto-electronic ring-oscillator. In addition, the photodiode-based opto-electronic ring-oscillator shows much faster signal processing characteristics than the case of CdS sensor. Our opto-electronic ring-oscillators show a wide range of tunable f_osc from 0.92 Hz to 114.42 Hz; moreover, it shows small signal-like light transfer characteristics as an analog signal process that can be useful in future opto-electronic device applications.     

Universal quantum control based on parametric modulation in superconducting circuits

As superconducting quantum circuits are scaling up rapidly towards the noisy intermediate-scale quantum(NISQ)era, the demand for electronic control equipment has increased significantly. To fully control a quantum chip of N qubits,the common method based on up-conversion technology costs at least 2 × N digital-to-analog converters(DACs) and N IQ mixers. The expenses and complicate mixer calibration have become a hinderance for intermediate-scale quantum control.Here we propose a universal control scheme for superconducting circuits, fully based on parametric modulation. To control N qubits on a chip, our scheme only requires N DACs and no IQ mixer, which significantly reduces the expenses. One key idea in the control scheme is to introduce a global pump signal for single-qubit gates. We theoretically explain how the universal gates are constructed using parametric modulation. The fidelity analysis shows that parametric single-qubit(two-qubit) gates in the proposed scheme can achieve low error rates of 10~(4), with a gate time of about 60 ns(100 ns).     

24 GHz宽波束阵列天线的设计

利用Rogers 5880为介质材料设计了一款应用于车载防撞雷达前端的圆极化微带阵列天线,该阵列天线采用直线阵结构,运用了多个四分之一波长阻抗变换器实现了阻抗匹配。仿真和测试结果表明: 该阵列天线的阻抗带宽(S₁₁ < -10 dB)为23.45~25.65 GHz,最大增益为15.54 dB;轴比带宽24.56~25 GHz,轴比最小为1.25 dB;第一副瓣电平小于-20 dB,E面半功率波瓣宽度为10°,H面波瓣宽度为75°,其尺寸为70.94 mm×14.72 mm×0.508 mm。该天线具有高增益、低副瓣、体积小、性能稳定等优点,在汽车防撞雷达系统中有广阔的应用前景。     

Arbitrary waveform generation for pre-compensation in optical fiber communication systems

The powerful capabilities of electronic digital signal processing and digital-to-analog conversion for implementing waveform generation in an optical transmitter are illustrated by considering pre-compensation for optical filtering, fiber dispersion, and nonlinear modulation dynamics.     

Optical Packet Routing Performance of an Optical Packet Switch Digital/ Analog-Conversion-Type With an Optical Header Processor (Wavelength Label Switch)

We demonstrate the routing operation of optical packets by an optical packet switch consisting of an optical digital-to-analog conversion-type header processor, a wavelength converter using an electrically-tunable laser, and an arrayed-waveguide grating router. A packet transfer by two -bit optical header was achieved for the first time.     

基于multisine激励与整周期采样的多频电阻抗成像系统设计

本文从周期信号的整周期采样无频谱泄露这一原理出发,提出基于multisine信号的整周期采样理论,从理论上推导出满足multisine整周期采样的采样率设置条件,构建了基于FPGA+数模转换器+模数转换器的整周期采样实现方法,研制了一种基于multisine激励和整周期采样的新型多频电阻抗成像(mfEIT)系统;设计了胡萝卜棒+黄瓜棒的双目标成像模型,并进行了多频时差成像和频差成像实验.实验表明,本mfEIT系统能够在一个基波周期(1 ms)内实现20个频率点(2—997 kHz)多目标组织边界的全频阻抗测量,成像结果可区分具有不同电特性生物组织的结构与位置.本文提出的基于multisine信号的整周期采样理论及其实现方法,只需一个multisine基波周期即可完成一次全频阻抗测量,为研制高速mfEIT系统奠定了理论和技术基础.     

Selective excitation of high-order modes in circular waveguides

The excitation of very high-order modes in circular waveguides has been performed in a cavity with a connected up-taper with a geometry similar to those used in gyrotrons. A Gaussian beam was coupled to the cavity which was made translucent by an array of holes. With the help of a special optics, the amplitude as well as the phase distribution of the beam was matched to the mode to be excited in the resonant cavity. By simple rotation of one mirror to adjust the phase distribution together with the change of frequency to match the resonance condition, a large number of modes could be produced with one experimental set-up. Field measurements in the output waveguide show a high mode purity of the radiation and confirm the calculations. The method can be used for cold tests of electrodynamic systems operating with these modes, e.g. quasi-optical converters for gyrotrons.     

Impedance of the microstrip line for magnetostatic backward volume waves

We study excitation of magnetostatic backward volume waves on the microstrip line. The relation between the current density in the line and the normal component of the magnetic induction is found. The impedance of the line per unit length, i.e., its reactance and radiation resistance per unit length, is represented as a functional of the current density. The dependence of the operating-wave radiation resistance on the transverse size of the line and the width of the dielectric gap is studied. The radiation resistances of multistrip array and meander-type converters of magnetostatic backward volume waves are calculated     

斜坡补偿电流模式控制开关变换器的动力学建模与分析

降压型、升压型和升压-降压型DC-DC变换器是应用广泛的基本开关DC-DC变换器.电流模式控制开关DC-DC变换器在较宽的电路参数范围内具有两个边界,基于开关切换前后电感电流的上升和下降斜率,建立了斜坡补偿电流模式控制开关DC-DC变换器的统一模型.该模型进行无量纲归一化处理后只有三个参数,可有效展示开关DC-DC变换器在电感电流连续传导模式(CCM)和电感电流不连续传导模式(DCM)时的动力学特性.利用此模型,导出了轨道状态发生转移时的两个分界线方程,由此确定了开关DC-DC变换器的稳定周期1域、CCM鲁棒混沌域和DCM弱混沌强阵发域三个工作状态区域.开关DC-DC变换器二维参数映射图和电流模式控制降压型DC-DC变换器的电路实验观察验证了由两条分界线划分工作状态域的正确性.     

Neutron detector array at IUAC: Design features and instrumentation developments

The characteristics and performance of the newly commissioned neutron detector array at IUAC are described. The array consists of 100 BC501 liquid scintillators mounted in a semi-spherical geometry and are kept at a distance of 175 cm from the reaction point. Each detector is a 5^″ × 5^″ cylindrical cell coupled to 5^″ diameter photomultiplier tube (PMT). Signal processing is realized using custom-designed home-made integrated electronic modules which perform neutron – gamma discrimination using zero cross timing and time-of-flight (TOF) technique. Compact custom built high voltage power supply developed using DC–DC converters are used to bias the detector. The neutrons are recorded in coincidence with fission fragments which are detected using multi-wire proportional counters mounted inside a 1 m diameter SS target chamber. The detectors and electronics have been tested off-line using radioactive sources and the results are presented.     

Symmetrical dynamics of peak current-mode and valley current-mode controlled switching dc-dc converters with ramp compensation

The discrete iterative map models of peak current-mode (PCM) and valley current-mode (VCM) controlled buck converters, boost converters, and buck--boost converters with ramp compensation are established and their dynamical behaviours are investigated by using the operation region, parameter space map, bifurcation diagram, and Lyapunov exponent spectrum. The research results indicate that ramp compensation extends the stable operation range of the PCM controlled switching dc--dc converter to D>0.5 and that of the VCM controlled switching dc--dc converter to D<0.5. Compared with PCM controlled switching dc--dc converters with ramp compensation, VCM controlled switching dc--dc converters with ramp compensation exhibit interesting symmetrical dynamics. Experimental results are given to verify the analysis results in this paper.     

Experimental thermionic energy converter without enclosure: A molecular beam supplied converter

Experimental thermionic energy converters of an open type, i.e. with no closely located surrounding walls, as proposed here, have many advantages compared to conventional enclosed converters. Interactions with and problems of the enclosure do not interfere with the fundamental plasma and surface processes, which can be studied efficiently in an open converter, for example by mass spectrometry, optical spectroscopy, electron energy analysis and surface analytical methods. An open converter has been built and tested, where the necessary alkali vapour is supplied by a molecular beam type source with 400 laser bored effusion holes. The source acts as collector in front of a directly heated emitter. An ignited mode behaviour can be reached easily. The examples of results presented for Mo and Pt emitters at 1600–1700 K, a Cs plasma and nickel collector give a power density of 1–2 W cm^–2 and a minimum barrier index of 1.95–2.1 eV and indicate a behaviour similar to enclosed converters. Thus, results for new surfaces, new additives etc. found in open converters should be of direct relevance for the development of normal enclosed converters.     

高速光学模数转换器的分析

详细分析了由x切LiNbO3干涉式共面波导行波调制器阵列构成的模数(A/D)转换器，包括其研究进展。采用保角变换方法分析了梯形共面波导电极参数(包括电极厚度、缓冲层厚度与中心电极和接地电极的边沿倾角β1，βg)与转换器的带宽、损耗、特征阻抗和驱动功率的关系。β1=βg=10°，电极厚度为3μm时，4位A/D转换器的工作带宽为7.3GHz，所需驱动功率为6.7W。数值仿真结果表明，采用梯形共面波导调制器阵列设计分辨率适中的高速A/D转换器是可行的。     

An optical multicast packet switching architecture shared with limited-range multi-wavelength converter and full-range wavelength converters

Optical packet switch with multicast capability can inspire a broad range of multipoint to multipoint applications in future optical networks. An optical multicast packet switching architecture, equipped with feedback shared small number of limited-range multi-wavelength converters (LMWCs) and output shared some full-range wavelength converters (FRWCs), is proposed for a wavelength-division multiplexed optical multicast network to improve multicast performance in the paper. The FRWCs are used to overcome the performance degradation in terms of packet loss probability due to only use LMWCs. In the architecture, the two converters are shared by all the multicast packets importing to the optical multicast switch node. A maximum bipartite matching with minimum edges weights strategy was designed to employ fewer wavelength converters and avoid useless degradation of optical signal quality for the architecture to improve the node performance. The simulation results show that the proposed architecture and its wavelength converter scheduling algorithm can reduce the multicast packet loss probability with relatively lesser wavelength conversion cost.     

Multi-parametric optimized design of FWM-based tunable all-optical wavelength converters for 40 Gbit/s ASK and DPSK signals

A full numerical optimization method for the design of FWM-based frequency converters for WDM systems is presented, taking into account specific system constraints set by the designer. The method is illustrated with the design of separate transparent frequency converters for 40 Gbit/s ASK and DPSK signals using Truewave fiber.     

160 Gbit/s binary-to-quaternary amplitude shift keying encoding in the optical domain

160?Gbit/s all-optical binary-to-quaternary amplitude shift keying format conversion is carried out in a nonlinear optical fiber. This scheme, which also acts as a 2 bit digital-to-analog convertor, has been confirmed through Q-factor measurements.