2.5 Gb/s Optical Transponder技术与设计

网络容量增长的同时也促进了光纤通信技术的发展,使得宽带传输和接入方式处于越来越重要的地位,如何有效地解决光纤干线上和大部分基于电缆局域网的信号转换成为亟待解决的问题,光收发器(opticaltransponder)很好地解决了宽带传输和接入的这一“瓶颈”问题。2.5 Gb/s是目前最流行的传输速率,其相应transponder用于SDH/Sonet OC-48/STM-16的光/电接口。文章介绍了2.5 Gb/s optical transponder的功能、结构等技术和相应的设计方案。

DESIGN ISSUES FOR BIT RATE-ADAPTIVE 3R O/E/O TRANSPONDER IN INTELLIGENT OPTICAL NETWORKS

This paper reported the design and implementation of a bit rate adaptive Optical Electronic Optical(O/E/O)transponder accomplishing almost full data rate transparency up to 2.5 Gb/s with 3R(Reamplifying,Reshaping and Retiming)processing in electronic domain.Based on the chipsets performing clock recovery in several continuous bit rate ranges,a clock and data regenerating circuit self adaptive to the bit rate of input signal was developed.Key design issues were presented,laying stress on the functional building blocks and scheme for the bit rate adaptive retiming circuit.The experimental results show a good scalability performance.

UNITED STABILIZING SCHEME FOR EDGE DELAY IN OPTICAL BURST SWITCHED NETWORKS

A novel scheme, namely united stabilizing scheme for edge delay, is introduced in optical burst switched networks. In the scheme, the limits of burst length and assembly time are both set according to certain qualifications. For executing the scheme, the conception for unit input bit rate is introduced to improve universality, and the assembly algorithm with a buffer safety space under the self-similar traffic model at each ingress edge router is proposed. Then, the components of burst and packet delay are concluded, and the equations that limits of burst length and assembly time should satisfy to stabilize the burst edge delay under different buffer offered loads are educed. The simulation results show that united stabilizing scheme stabilizes both burst and packet edge delay to a great extent when buffer offered load changes from 0.1 to 1, and the edge delay of burst and packet are near the limit values under larger offered load, respectively.

Acceleration of optical coherence tomography signal processing by multi-graphics processing units

A multi-GPU system designed for high-speed,real-time signal processing of optical coherencetomography(OCT)is described herein.For the OCT data sampled in linear wave numbers,themaximum procesing rates reached 2.95 MHz for 1024-OCT and 1.96 MHz for 2048-OCT.Data sampled using linear wavelengths were re-sampled using a time-domain interpolation method and zero-padding interpolation method to improve image quality.The maximum processing rates for1024-OCT reached 2.16 MHz for the time-domain method and 1.26 MHz for the zero-paddingmethod.The maximum processing rates for 2048-0CT reached_1.58 MHz,and 0.68 MHz,respectively.This method is capable of high-speed,real-time processing for O CT systems.

Remote I/O Unit for Optical Fiber Demmunication

Abstract:Based on optical fiber technology, the main electric circuit of the remote I/O unit controller is studied. And the application of the system is illustrated.

Optical transmission through basic-structural-unit superlattices

In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence. Based on these new BCs we propose a type of basic-structural-units （BSUs） and investigate the optical transmission of the one-dimensional （1D） superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength （CW） will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices.

Optic nerve sheath diameters in nontraumatic brain injury:A scoping review and role in the intensive care unit

BACKGROUND Neuromonitoring in medical intensive care units is challenging as most patients are unfit for invasive intracranial pressure(ICP)modalities or unstable to transport for imaging.Ultrasonography-based optic nerve sheath diameter(ONSD)is an attractive option as it is reliable,repeatable and easily performed at the bedside.It has been sufficiently validated in traumatic brain injury(TBI)to be incorporated into the guidelines.However,currently the data for non-TBI patients is inconsistent for a scientific recommendation to be made.AIM To compile the existing evidence for understanding the scope of ONSD in measuring ICP in adult non-traumatic neuro-critical patients.METHODS PubMed,Google Scholar and research citation analysis databases were searched for studies in adult patients with non-traumatic causes of raised ICP.Studies from 2010 to 2024 in English languages were included.RESULTS We found 37 articles relevant to our search.The cutoff for ONSD in predicting ICP varied from 4.1 to 6.3 mm.Most of the articles used cerebrospinal fluid opening pressure followed by raised ICP on computed tomography/magnetic resonance imaging as the comparator parameter.ONSD was also found to be a reliable outcome measure in cases of acute ischaemic stroke,intracerebral bleeding and intracranial infection.However,ONSD is of doubtful utility in septic metabolic encephalopathy,dysnatremias and aneurysmal subarachnoid haemorrhage.CONCLUSION ONSD is a useful tool for the diagnosis of raised ICP in non-traumatic neuro-critically ill patients and may also have a role in the prognostication of a subset of patients.

光通信用10Gbit/s Transponder的设计

本文分析了在高速光模块设计中介质损耗和微带结构对信号的影响,并对PCB中信号串扰模型的参数进行了计算.解决了高速光模块设计的一些关键问题,设计出满足MSA的300-pin transponder,并对模块进行了一系列性能和指标测试.测试结果表明,该模块完全满足SDH/SONET(STM-64/OC-192)以及10G Ethernet应用要求.

Experimentation of a 1-pixel bit reconfigurable ternary optical processor

A detailed experiment of 1-pixel bit reconfigurable ternary optical processor （TOP） is proposed in the paper. 42 basic operation units （BOUs） and 28 typical logic operators of the TOP are realized in the experiment. Results of the test cases elaborately cover the every combination of BOUs and all the nine inputs of ternary processor. Both the experiment process and results analysis are given in this paper. The experimental results demonstrate that the theory of reconfiguring a TOP is valid and that the reconfiguration circuitry is effective.

Spatio-Temporal Variations in the Associations between Hourly PM_2.5and Aerosol Optical Depth (AOD) from MODIS Sensors on Terra and Aqua

Recent studies have explored the relationship between aerosol optical depth (AOD) measurements by satellite sensors and concentrations of particulate matter with aerodynamic diameters less than 2.5 μm (PM2.5). However, relatively little is known about spatial and temporal patterns in this relationship across the contiguous United States. In this study, we investigated the relationship between US Environmental Protection Agency estimates of PM2.5 concentrations and Moderate Resolution Imaging Spectroradiometer (MODIS) AOD measurements provided by two NASA satellites (Terra and Aqua) across the contiguous United States during 2005. We found that the combined use of both satellite sensors provided more AOD coverage than the use of either satellite sensor alone, that the correlation between AOD measurements and PM2.5 concentrations varied substantially by geographic location, and that this correlation was stronger in the summer and fall than that in the winter and spring.

TIME-DOMAIN INTERPOLATION ON GRAPHICS PROCESSING UNIT

The signal processing speed of spectral domain optical coherence tomography(SD-OCT)has become a bottleneck in a lot of medical applications.Recently,a time-domain interpolation method was proposed.This method can get better signal-to-noise ratio(SNR)but much-reduced signal processing time in SD-OCT data processing as compared with the commonly used zeropadding interpolation method.Additionally,the resampled data can be obtained by a few data and coefficients in the cutoff window.Thus,a lot of interpolations can be performed simultaneously.So,this interpolation method is suitable for parallel computing.By using graphics processing unit(GPU)and the compute unified device architecture(CUDA)program model,time-domain interpolation can be accelerated significantly.The computing capability can be achieved more than 250,000 A-lines,200,000 A-lines,and 160,000 A-lines in a second for 2,048 pixel OCT when the cutoff length is L=11,L=21,and L=31,respectively.A frame SD-OCT data(400A-lines×2,048 pixel per line)is acquired and processed on GPU in real time.The results show that signal processing time of SD-OCT can befinished in 6.223 ms when the cutoff length L=21,which is much faster than that on central processing unit(CPU).Real-time signal processing of acquired data can be realized.

A novel algorithm for Ethernet-passive-optical-network dynamic bandwidth allocation based on threshold

The Ethemet passive optical network （EPON） is the next generation of broad-band network technique. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units （ONUs）. This article provides a novel dynamic bandwidth allocation algorithm, i.e. threshold dynamic bandwidth allocation （TDBA）, which is based on adaptive threshold, to increase resource utilization. The algorithm uses ONU data-transmitting rate to adjust optical line terminal （OLT） receiving data threshold from an ONU. Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a l 0G EPON system.

Performance Analysis of WDM RoF-EPON Link with and without DCF and FBG

Performance of WDM ethernet passive optical network (EPON) with radio over fiber (RoF) optical link has been analyzed with the use of dispersion compensating fiber (DCF) and fiber bragg grating (FBG) to compensate the dispersion and four wave mixing. With the use of DCF and FBG, performance of the system is improved by 77.67%. Results are compared with and without DCF + FBG for different optical power and fiber length. The BER, Q factor and eye diagrams have been obtained for evaluating the performance of the system.

A passive optical network based on optical code division multiplexing and time division multiple access technology

A passive optical network （PON） scheme based on optical code division multiplexing （OCDM） for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM technology to guarantee the security, while the upstream traffics pass through the same optical fiber by the common time division multiple access （TDMA） technology to decrease the cost. This schemes are denoted as OCDM/TDMA-PON, which can be applied to an optical access network （OAN） with full services on demand, such as Internet protocol, video on demand, tele-presence and high quality audio. The proposed OCDM/TDMA-PON scheme combines advantages of PON, TDMA, and OCDM technology. Simulation results indicate that the designed scheme improves the OAN performance, and enhances flexibility and scalability of the system.

Optimization of Disjoints Using WDM-PON in an Optical Network

An optical network is a type of data communication network built with optical fibre technology. It utilizes optical fibre cables as the primary communication medium for converting data and passing data as light pulses between sender and receiver nodes. The major issue in optical networking is disjoints that occur in the network. A polynomial time algorithm Wavelength Division Multiplexing-Passive Optical Networking (WDM-PON) computes disjoints of an optical network and reduces the count of disjoints that occur in the network by separating Optical Network Units (ONU) into several virtual point-to-point connections. The Arrayed Waveguide Grating (AWG) filter is included in WDM-PON to avoid the traffic in the network thereby increasing the bandwidth capacity. In case of a failure or disjoint Ant Colony Optimization (ACO) algorithm is used to find the optimized shortest path for re-routing. For enhanced security, modified Rivert Shamir Adleman (RSA) algorithm encrypts the message during communication between the nodes. The efficiency is found to be improved in terms of delay in packet delivery, longer optical reach, optimized shortest path, packet error rate.

星载激光雷达视轴监测系统设计

提出了一种针对星载激光雷达在轨高精度光轴监测与标定需求的多光轴监测方法,该方法基于主动激光光源。通过使用785 nm的激光,分束后分别照射到星敏感器的基准棱镜和接收望远镜的取光棱镜,反射信号被聚焦至监视相机的焦平面,实现了对接收光轴及星敏光轴的精确监测。此外,监视相机还同步采集发射激光的部分能量,用于测量监测发射光轴。文中详细描述了光学系统的设计流程及关键组件的优化方案,并通过地面真空环境试验及在轨监测数据进行了验证。设计结果表明,各监视通道的成像质量达到了衍射极限,收发光轴的设计精度分别为0.09μrad和2.28μrad,关键组件取光棱镜的温控精度达到了±0.2℃。地面的真空热光试验结果进一步验证了该方案的高精度光轴监视能力,收发光轴的监测精度均优于3μrad。最后通过分析激光雷达入轨后的测量数据,确认了视轴监测系统的工作稳定性,成功实现了在轨的高精度光轴监视。该研究成果为星载激光雷达提供了一种有效的在轨高精度光轴监测与标定解决方案。

基于应变增敏的双层十字型FBG触觉感知单元

触觉感知是仿生智能感知的重要内容,为了提高光纤布拉格光栅(Fiber Bragg Grating, FBG)触觉感知灵敏度,结合机器手指尖触觉感知需求,提出了一种应变增敏的FBG触觉感知单元。基于应变增敏机理和触觉感知机理分析,设计了一种基于应变增敏的双层十字型FBG触觉感知单元,采用刚性球型多点增压结构进行应变增敏。利用仿真分析方法优化了FBG空间分布,并对感知单元进行了静力学和热力学仿真。最后搭建了触觉感知实验平台,结合机器手完成了温度-力触觉协同感知实验。仿真和实验结果表明,FBG1和FBG2的力触觉感知灵敏度分别为18.069 nm/MPa和1.065 nm/MPa,温度感知灵敏度为11.256 pm/℃和11.153 pm/℃。该触觉感知单元有效提高了触觉感知灵敏度,具有良好的线性度和重复性。

基于OISL-OSU的通算一体卫星路由优化算法

为了进一步解决多星及星地间通信和计算系统资源的高度整合与互馈增强问题,提出了一种基于卫星间光链路光业务单元(OISL-OSU)的通算一体卫星路由优化算法——OISL-DDPG算法。该算法采用深度确定性策略梯度(DDPG)优化方法,提高了卫星光网络QoS性能。仿真实验表明:采用基于时间窗口的网络切片方法符合国内低轨星座真实网络运行状态;与最小跳数算法相比,所提出的算法以增加微小时延为代价,获得更高的链路利用率和链路占用率;与多约束最短路由优先(MCSPF)算法相比,该算法的收敛性更好,时延和丢包率更低。

The Educational Adaptive-optics Solar Telescope at the Shanghai Astronomy Museum

The Educational Adaptive-optics Solar Telescope(EAST)at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021.It is a 65-cm-aperture Gregorian solar telescope for scientific education,outreach,and research.The telescope system is designed in an“open”format so that the solar tower architecture can be integrated with it,and visitors can watch the observations live from inside the tower.Equipped with adaptive optics,a high-resolution imaging system,and an integral field unit spectro-imaging system,this telescope can obtain high-resolution solar images in the TiO and Hαbands,and perform spectral image reconstruction using 400 optical fibers at selected wavelengths.It can be used not only in public education and scientific outreach but also in solar physics research.

Gain-enabled optical delay readout unit using CMOS-compatible avalanche photodetectors

A compact time delay unit is fundamental to integrated photonic circuits with applications in,for example,optical beam-forming networks,photonic equalization,and finite and infinite impulse response optical filtering.In this paper,we report a novel gain-enabled delay readout system using a tunable optical carrier,low-frequency RF signal and CMOS-compatible photodetectors,suitable for silicon photonic integration.The characterization method relies on direct phase measurement of an input RF signal and thereafter extraction of the delay profile.Both integrated silicon and germanium photodetectors coupled with low-bandwidth electronics are used to characterize a microring resonator-based,true-time delay unit under distinct ring–bus coupling formats.The detectors,used in both linear and avalanche mode,are shown to be successful as optical-to-electrical converters and RF amplifiers without introducing significant phase distortion.For a Si–Ge separate-absorption-charge-multiplication avalanche detector,an RF amplification of 10 dB is observed relative to a Ge PIN linear detector.An all-silicon defect-mediated avalanche photodetector is shown to have a 3 dB RF amplification compared to the same PIN detector.All ring delay measurement results are validated by full-wave simulation.Additionally,the impact of photodetector biasing and system linearity is analyzed.