Design of a data acquisition unit using photonic devices

In this paper, the design of a stand-alone optical data acquisition unit is presented. The system hardware consists of optical analog-to-digital converter inputs, optical digital bidirectional switches, analog and digital inputs/outputs and a microcontroller-based system. The unit software consists of several tasks that enable the user through the input-drivenmenu to read, store, analyze, process, and display the incoming data. This unit can be used in different applications, such as signal processing, underwater acoustics, aerospace guidance, optical computing and color sorting.     

基于TMS320F2812控制器的自动调光系统设计

为满足面阵CCD航空相机获得清晰图像的需要,设计一种以数字处理芯片TMS320F2812为核心调光控制器,结合可编程逻辑器件EPM7128完成逻辑运算与电平转换,集成光敏二极管芯片OPT301M为检光元件,模数转换器AD7865将模拟量转换为数字量,直流电机控制单帘幕快门帘缝速度,光电编码器反馈速度信号,程序代码实现调光算法与控制的自动调光控制系统。实验表明,在180r/min的阶跃输入信号下,得到调节时间为0.095s, 最大超调量为7.2%,速度误差为1.08r/min,其特性参数满足性能指标的要求。     

Active noise control in a duct by an analog neural network circuit

Conventional active noise control (ANC) in ducts has been realized with digital signal processing. The physical size of the conventional ANC systems is usually large owing to the signal processing interval, and the cost of the system depends on the price of the digital signal processor (DSP). This paper proposes a new ANC system with an analog neural network circuit, which will process signals in short time periods without DSP. The proposed neural network circuit has a simple structure consisting of analog multipliers and an integrator, and we simulated the performance of the circuit by HSPICE. We also fabricated a circuit connected to a real duct and confirmed operation of the proposed ANC system.     

Real time correlation filter for optical particle counter

Particle signals are detected by two parallel measuring chains which consist of a detector and analog to digital converter. We have used OPT101 as photodiode and ADS7870 for A/D converter and the output signal from two parallel measuring chains is processed by on line correlation filter. This filter works as real time systems. A correlation algorithm has been applied for this work. The signal to noise ratio has been increased by applying correlation filter. The gain of the filter has been improved by introducing digital signal processing.     

Optical flip-flop and astable nultivibrator functions by vertical and direct integration of heterojunction phototransistors and laser diodes

A optoelectronic integrated device in which six heterojunction phototransistors and two laser diodes are vertically and directly integrated is developed to achieve new functions important for optical signal processing and optical computing. It is demonstrated that the device has a bistable flip-flop function, in which the output portion is switched alternately by the corresponding optical input. The function is extended to a tristable flip-flop, which is especially important for multistable logic, by using multiple HPTS and their internal optical and/or electrical couplings. Moreover, an astable multivibrator function or a self-oscillating function, is successfully demonstrated by applying the interconnecting technique to the bistable flip-flop function.     

Optical orthogonal frequency division multiplexing demultiplexer using slab star coupler-based optical discrete Fourier transform circuit

We demonstrate an optical orthogonal frequency division multiplexing (OFDM) demultiplexer with an optical discrete Fourier transform circuit fabricated using silica planar lightwave circuit technology. This compact device can process an arbitrary number of subcarriers. The operation of a ten-channel device is demonstrated by demultiplexing a 100 Gbit/s (10 subcarrier × 10 Gbits/s) OFDM signal. We also discuss a main factor affecting characteristics degradation of the device.     

二维材料类脑器件

研究类脑器件是构建一个能够与大脑相媲美的类脑信息处理系统的重要基础。二维材料凭借优异的电学与光电特性、可多自由度调控以及可三维垂直集成等优势,为设计多功能的类脑器件提供了丰富的材料和机制选择。文章围绕二维材料及异质结类脑器件的设计展开,通过总结最近的重要研究进展,探究该领域未来可能面临的机遇与挑战。     

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.     

Amorphous InGaZnO_4 Neuron Transistors with Temporal and Spatial Summation Function

Amorphous InGaZnO_4 neuron transistors based on multi-gate electric-double-layer modulation are fabricated by photolithography processes. The sweeping rate dependent output current and hysteresis loop are observed due to the proton dynamic process in the SiO_2 nanogranular electrolyte. Temporal summation such as paired-pulse facilitation is mimicked in the neuron transistor with one presynaptic input. At the same time, supralinear spatial summation of two presynaptic inputs is also successfully mimicked in the neuron transistor with two presynaptic inputs. Our InGaZnO_4 neuron transistors with temporal and spatial summation function are interesting for the brain-inspired neuromorphic system.     

基于六角氮化硼二维薄膜的忆阻器

报道了一种基于多层六角氮化硼(h-BN)二维薄膜的忆阻器件.该器件不需要电预处理过程,且具有自限流的双极性阻变行为;具有较好的抗疲劳性和较长的数据保持时间.该器件在脉冲编程条件下具有模拟转变特性,即在连续的电压脉冲下器件的电阻态能被连续地调控,使得该器件能够模仿神经网络系统中的神经突触权重变化行为.综上所述,基于多层h-BN的忆阻器具有应用在非易失性存储和神经计算中的潜力.     

Recent progress on two-dimensional neuromorphic devices and artificial neural network

Mimicking biological synapses with microelectronic devices is widely considered as the first step in hardware building artificial neuromorphic networks, which is also the basis of brain-inspired neuromorphic computing. Numerous artificial neurons and synapses making up an artificial neuromorphic network have been gained wide attention due to their powerful and efficient data processing capabilities. Recently, artificial synapses, especially memristor-type and transistor-type synapses based on multifarious two-dimensional (2D) materials have been paid much attention. The unique properties of 2D materials make devices perform well in learning ability and power efficiency when mimicking synaptic behaviors, which highlights the feasibility of 2D neuromorphic devices in constructing artificial neuromorphic networks. Herein, the basic structures and principles of biological synapses are introduced, and the definitions of synaptic behaviors in synaptic electronic devices are discussed. Then, the progress of 2D memristor-type and transistor-type neuromorphic devices involving their device architecture, neuromorphic operational mechanism, and promising applications is reviewed. Finally, the future challenges of artificial synaptic devices based on 2D materials are discussed briefly.     

Integrated optoelectronic circuit forecast

A market research study was conducted, leading to a 10-year forecast of worldwide integrated optoelectronic circuit (IOEC) market and application trends. Four IOEC categories were considered: lightwave, imaging array, digital IC interface optical bus, and other devices. It was concluded that worldwide IOEC production will reach $1.71 billion by 1997. It was also concluded that lightwave IOECs will be the leading device category, with commercial communication the leading application.     

多核DSP高速实时信号处理系统设计

介绍了基于TI公司多核定点DSP(TMS320C6474)的高速实时数字信号处理系统。系统利用FPGA作为控制单元和转接芯片,通过SRIO接口作为DSP芯片的数据输入输出接口,具有信号处理能力超高、输入输出接口简洁、以及存储能力较大的优点。在软件实现中,利用了乒乓数据吞吐,静态内存分配技术和三核软件同步机制,通过优化算法,高效地实现了三核DSP实时信号处理,计算效率达到了设计要求。在项目图像信号实时处理中得到了成功应用,取得了良好的效果。     

基于忆容器件的神经形态计算研究进展

人工智能的快速发展需要人工智能专用硬件的快速发展,受人脑存算一体、并行处理启发而构建的包含突触与神经元的神经形态计算架构,可以有效地降低人工智能中计算工作的能耗.记忆元件在神经形态计算的硬件实现中展现出巨大的应用价值;相比传统器件,用忆阻器构建突触、神经元能极大地降低计算能耗,然而在基于忆阻器构建的神经网络中,更新、读取等操作存在由忆阻电压电流造成的系统性能量损失.忆容器作为忆阻器衍生器件,被认为是实现低耗能神经网络的潜在器件,引起国内外研究者关注.本文综述了实物/仿真忆容器件及其在神经形态计算中的最新进展,主要包括目:前实物/仿真忆容器原理与特性,代表性的忆容突触、神经元及神经形态计算架构,并通过总结近年来忆容器研究所取得的成果,对当前该领域面临的挑战及未来忆容神经网络发展的重点进行总结与展望.     

数字式声呐中的升采样率处理

升采样率处理是某些数字式声呐的必不可少的预处理.本文给出整倍数升采样率运算的基本原理和理论结果。指出,升采样率处理的好坏不仅取决于窗函数的长度,也还和输入信号的功率谱密度有关.为实现升采样率处理,可以采用几种不同方法,文中指出用输入样本补零和窗函数卷积的方法是有效的.在数字计算机上的模拟取得了良好的结果.这种方法便于用专用数字信号处理芯片实现,并且对输入、输出采样率的选取上有很宽容的余地。     

Integrated optoelectronic circuit forecast

A market research study was conducted, leading to a 10-year forecast of worldwide integrated optoelectronic circuit (IOEC) market and application trends. Four IOEC categories were considered: lightwave, imaging array, digital IC interface optical bus, and other devices. It was concluded that worldwide IOEC production will reach $1.71 billion by 1997. It was also concluded that lightwave IOECs will be the leading device category, with commercial communication the leading application.     

Kerr nonlinear switch based on ultra-compact photonic crystal directional coupler

In this paper, an all optical switch based on nonlinear photonic crystal directional coupler has been simulated and analyzed by the finite difference time domain (FDTD) method. The lunched pump signal increases the refractive indices of the central row of the coupler, due to nonlinear Kerr effect, hence the coupler works in the nonlinear conditions and lightwave guides to the other output port. We have tried to increase the coupling efficiency and reduce the required power in the nonlinear status by optimizing the bends structure and increasing the interaction between dielectric and lightwave signal. Therefore, the input signal beam can be controlled to be exchanged between two output ports to earn the highest output power ratio and the smallest amount of power required for nonlinear performance, the physical length of the coupler is determined to be 20a, where a is the structure lattice constant.     

Optoelectronic multiplexer for digital data processing based on lipid crystal pixels and optical fiber elements

In this work, we present an optoelectronic digital multiplexer 4:1 based on a multipixel nematic liquid crystal cell. This device uses two optical control signals to select one among four possible optical data inputs. These data signals are generated by four red LEDs, which are guided through plastic optical fiber towards liquid crystal pixels. For our purpose, only four pixels of the cell will be used to modulate the optical signal across them. Each pixel will be addressed by a square waveform coming from the conditioning circuit managed by a microcontroller system. The electronic control allows the multiplexer to work as as simple two input logical gates such as AND, NAND, OR, NOR, XOR and XNOR. The operation time of the device is limited by the response time of LC cell that is in the millisecond range.     

All optical alternative approach of conducting NAND and NOR logic gates with phase encoding principle

All optical logic gates are the most important building blocks for conducting all optical digital and analog signal processing and computing. It has several uses in the high speed communication system. In last few years various non-linear properties of semiconductor optical amplifier have been utilized for realization of all optical logic gates exploiting different type's optical modulations. In such connection optical phase encoding technique drew more attention in last few years as it shows higher receiver sensitivity and extended tolerance limit in long-haul fiber transmission systems. In this communication the authors have proposed an alternative approach for conducting all optical logic gates with phase encoded inputs by the exploitation of the four wave mixing (FWM) property in semiconductor optical amplifier (SOA).     

Digital detection and processing of multiple quadrature harmonics for EPR spectroscopy

A quadrature digital receiver and associated signal estimation procedure are reported for L-band electron paramagnetic resonance (EPR) spectroscopy. The approach provides simultaneous acquisition and joint processing of multiple harmonics in both in-phase and out-of-phase channels. The digital receiver, based on a high-speed dual-channel analog-to-digital converter, allows direct digital down-conversion with heterodyne processing using digital capture of the microwave reference signal. Thus, the receiver avoids noise and nonlinearity associated with analog mixers. Also, the architecture allows for low-Q anti-alias filtering and does not require the sampling frequency to be time-locked to the microwave reference. A noise model applicable for arbitrary contributions of oscillator phase noise is presented, and a corresponding maximum-likelihood estimator of unknown parameters is also reported. The signal processing is applicable for Lorentzian lineshape under nonsaturating conditions. The estimation is carried out using a convergent iterative algorithm capable of jointly processing the in-phase and out-of-phase data in the presence of phase noise and unknown microwave phase. Cramér-Rao bound analysis and simulation results demonstrate a significant reduction in linewidth estimation error using quadrature detection, for both low and high values of phase noise. EPR spectroscopic data are also reported for illustration.