Experimental evaluation of resolution enhancement of a phase-shifted all optical analog-to-digital converter using an electrical analog-to-digital converter array

A resolution-improvement scheme of a phase-shifted analog-to-digital converter （ADC） is presented and experimentally demonstrated. To improve resolution via the scheme, the optical output of each quanti- zation channel is quantized by an electrical ADC with multiple thresholds instead of a comparator. A 9.9-GHz sinusoidal analog signal is sampled and quantized using the proposed enhancement scheme. The effective number of bits of 4.31 and the spur-free dynamic range of 40.89 dB are obtained, thus indicating an improvement of 0.66 bits and 7.47 dR. resnectivelv.     

40 Gb/s光时分复用系统中两级偏振模色散自适应补偿实验研究

偏振模色散效应严重制约着长距离高速光纤通信的发展,偏振模色散的自适应补偿成为光通信领域研究的焦点。利用两阶段偏振模色散补偿器,采用6个自由度的粒子群优化算法(PSO),通过在线监测搜索光纤链路信号的偏振度极值作为反馈控制信息,在40Gb／s归零码高速光纤传输链路中成功实现了ms量级的偏振模色散自适应补偿。补偿前后采用庞加莱球法测量光纤链路中偏振模色散量,测量结果表明在信号中心波长1560．5nm处,差分群时延补偿前后测量值分别为21ps和1．3ps,而二阶偏振模色散补偿前后测量值分别为266ps^2和43．5ps^2。补偿后实验链路中的一阶和二阶的偏振模色散同时得到不同程度的补偿,并且系统的总的功率代价在误码率为10^-9时小于1dB。     

All-optical queue buffer using optical threshold functions and wavelength converters

A modular,cascadable,and self-controlled optical queue buffer is proposed,which can solve the packet contention at a 2×1 optical node.Controlled by incoming optical packets,the buffer can realize firstin-first-out queue buffering without the necessity of external control signals.By using optical threshold functions and wavelength converters based on semiconductor optical amplifier,the push and pop operations of packets on queue can both be achieved.In addition,preliminary experiment is carried out.     

东方超环上低杂波驱动等离子体环向旋转实验研究

旋转和旋转剪切能抑制磁流体不稳定性和增强等离子体约束.低杂波电流驱动作为未来聚变堆上可能的旋转驱动手段,探索低杂波在现有托卡马克装置上驱动等离子体旋转的驱动机制,可以为未来的聚变堆上旋转预测提供重要参考.在东方超环托卡马克装置上,早期发现了2.45 GHz的低杂波能有效驱动等离子体旋转的现象,认为是边界旋转的改变导致芯部旋转的同电流方向的增加造成的.更高频率下4.6 GHz低杂波电流驱动可以更有效地驱动同电流方向的等离子体旋转.本论文分析在欧姆背景等离子体下,不同功率的低杂波对等离子体环向旋转的影响,研究安全因子剖面变化对环向旋转的关系,利用功率调制获得了低杂波驱动旋转实验中的环向动量输运系数变化情况,发现环向动量扩散系数(χφ)、环向动量箍缩系数(Vpinch)的数值大小趋势是从芯部向靠外的区域逐渐变大.这与低杂波驱动环向旋转时,环向旋转速度由靠外的区域向芯部传递的特性吻合.     

快速真空紫外光谱诊断在EAST实验的初步应用

为了在EAST装置上开展高参数放电条件下边界杂质辐射的实验研究,发展了真空紫外(VUV)光谱诊断系统.该系统采用了焦距为200mm的Seya-Namioka型VUV光谱仪,并配备了600g·mm-1凹面全息光栅,所能观测的波长范围为50～700nm,覆盖真空紫外、近紫外和可见光波段.系统在垂直方向的观测范围为Z=-35...