解决光突发交换竞争的新模型

针对光突发中的竞争问题，提出了一种分割反馈模型，相应地建立了数学分析模型，并进行了仿真与性能分析。结果表明这一模型是解决光突发交换中竞争问题的一个较佳方案。     

椭圆偏振光注入下VCSELs的偏振开关特性研究

本文基于自旋反转模型,理论研究了椭圆偏振光注入下垂直腔面发射激光器(VCSELs)的偏振开关特性。研究结果表明:在X偏振模占主导的VCSELs中,采用椭圆偏振光注入时,随着注入偏转角度θ的增大,VCSELs发生偏振开关所需的最小注入系数(ηin min)值将呈现减小的趋势;当注入偏转角度θ值固定时,随着注入光与VCSELs中心频率之间的频率失谐量从负值变化到正值,ηin min值总体呈现出先减小后增大的趋势,而ηin min的极小值出现在了注入光的频率靠近VCSELs的Y偏振模频率的附近。因此,改变注入偏转角度及注入频率失谐量均可以实现对VCSELs的偏振开关的有效调控。     

电力系统中MEMS光开关切换路径优化控制的方法

针对电力系统中微机电系统(MEMS)光开关在切换备纤时可能受到光控信号的影响而造成光时域反射仪(OTDR)发生损坏的问题,文章提出了一种电力系统中MEMS光开关切换路径优化控制的方法,在对MEMS光开关进行完整的扫描后得到其精确的光信号通道功率等高图,然后再对其切换路径进行优化控制,使得MEMS光开关可以在平衡控制通道切换时间的前提下使入射光沿相对通道隔离度最高的最佳路径进行切换控制,同时也可以在保证切换时间的前提下将MEMS光开关在切换时对其他通道的影响降到最低,并且即使在通道环境非常复杂的情况下也不受影响。     

自调Q掺铒光纤环形激光器的研究

对一种结构新颖的自调Ｑ掺铒光纤环形激光器的工作机理进行了研究。结果表明，该激光器中由光纤耦合器和半导体激光器芯片组成的反馈光路，依据光纤环中相向传输激光场相差的不同，对进入掺铒光纤的激光场进行选择反馈，在光纤环中激发幅度不断增强的光脉冲，引起掺铒光纤的瞬态增益饱和，实现激光器的自调Ｑ。理论分析能较好地解释实验中观察到的现象。     

Complete polarization mode control of long-wavelength tunable vertical-cavity surface-emitting lasers over 65-nm tuning, up to 14-mW output power

We experimentally demonstrate a stable polarization mode operation in long-wavelength tunable vertical-cavity surface-emitting lasers over a 65-nm tuning range and the entire output power range (< 14.6 mW) at room temperature. The polarization mode control was achieved by utilizing anisotropic gain properties of quantum wells due to the difference in bond lengths between the constituent atoms at the interfaces combined with uni-axial external strain induced by a stressor. The experiments were conducted to verify this newly proposed polarization control scheme based on the spin flip model (SFM) developed to incorporate the detailed gain properties, cavity standing wave effect, self-heating effect, and strain effect. The experimental results on the tuning characteristics of polarization switching behavior and output powers were reproduced in highly agreeable manner by simulations. The relative importance of the external strain, interfacial strain at quantum wells, and the wavelength dependence of gain anisotropy are also discussed. It is also shown that the fast spin relaxation times for InP-based vertical-cavity surface-emitting lasers (VCSELs) was responsible for the inhibition of elliptic polarization states often observed for GaAs-based VCSELs. The effectiveness of the polarization control scheme was highlighted by the observed high polarization suppression ratio of 34 dB maintained for the entire wavelength and pump power ranges during the reliability testing over 2000 h. The influence of the elliptic polarization state for the optical pump laser was detected which could be explained as a memory effect of the spin-polarized electrons, supporting the validity of the SFM.     

自适应混合光交换

当前的混合光交换只是简单地把光电路交换和光突发交换叠加在一起,其复杂度高.并且不能有效支持突发性强的业务.针对这种缺陷,本文提出了一种自适应混合光交换方式.自适应混合光交换的入口边缘节点监测一对入口边缘节点和出口边缘节点之间的业务流量的大小,自适应地调整光交换方式.在最小突发长度最大汇聚时间算法的基础上,提出了自适应混合光交换的汇聚算法,以提高光路的利用率和有效支持突发性强的业务.同时提出了数据信道调度算法,它能统一为光路和数据突发预留资源,并降低了混合光交换的复杂度,提高了网络性能.仿真结果表明,与光突发交换相比,自适应光交换能有效降低IP包丢失率和端对端时延.     

线性变化电流注入改善分布反馈半导体光放大器的滤波及双稳特性

提出一种基于线性变化电流注入以改善分布反馈半导体光放大器的滤波及双稳特性的实现方案，并借助耦合模方程及载流子速率方程，将该方案与相移、啁啾非均匀分布反馈半导体光放大器的特性作了分析比较。结果表明，该方法既有与相移效应相似的透射谱，又有与啁啾效应相似的频带较宽、双稳环上支较平坦的特点，且有效提高了开关对比度。     

Novel MEMS L-switching matrix optical cross-connect architecture: design and analysis-optimal and staircase-switching algorithms

Free-space optical cross connect (OXC) for optical switching has shown promise in replacing traditional electronic switching fabrics. Micromachined optical switches offer superior performance in terms of bit rate and protocol transparency, which make them futureproof; however, they suffer from nonuniformity in port-to-port optical losses, which limit their use in large-scale optical connects. Recent reports on a novel two-dimensional (2-D) OXC architecture, L-switching matrix, presented that it can significantly improve nonuniformity in optical losses among all output ports. The drawback of L-switching matrix is that it is rearrangeably nonblocking (RNB) and not strictly nonblocking. This paper presents solutions to optimize its switching algorithms. A staircase-switching algorithm is proposed to minimize the occurrence of internal blocking conditions.     

Optical switching technology comparison: optical MEMS vs. other technologies

Optical switching technologies are very crucial to future mobile broadband all-optical IP networks. Many different optical switching technologies are currently available or under development. The main purpose of the article is to conduct performance comparisons on optical switching technologies in terms of basic performance, network requirements, and system requirements based on a literature survey. The technologies include switching based on optical microelectromechanical systems (MEMS), thermal optical switching, electro-optic switching, and acousto-optic switching technologies. Each optical switching technology has unique performance characteristics specific to the utilized optical phenomena. It might be crucial to integrate some technologies together to achieve a better solution for optical switching. Optical switching is a very hot topic attracting much research effort. Optical MEMS-based switching technology might be one of the most promising approaches at present. Many new optical switching technologies might be created in the near future. Through the impact of nanotechnology, some innovative approaches to optical switching might emerge.     

外加电场下垂直腔面发射激光器的偏振转换电流

电光效应双折射可以控制垂直腔面发射激光器的偏振特性。本文计算了作用在垂直腔面发射激光器（VCSEL）的上面的分布格反射镜（DBR）上的外加电场产生的双折射,并在此基础上通过对自旋反转模型（SFM）的修正,得到面发射激光器在外加电场存在时的偏振转换电流。     

反激型开关电源反馈回路的改进

介绍了一种基于PWM控制芯片UC3842的反激式开关电源的反馈控制回路改进设计。该电路采用光耦和电压基准TL431组成反馈网络，具有反馈精度高，动态响应快，实用性强等优点。     

High-Performance Hybrid-Switching Optical Router for IP over WDM Integration

Because pure electrical routers with their bandwidth limitations can hardly keep up with the tremendous traffic growth in the Internet, optical routers based on various optical switching techniques including optical wavelength switching (OWS), optical burst switching (OBS), and optical packet switching (OPS) have been suggested to cope with this problem. However, because OBS and OPS are both in their early experimental phase and OWS only provides coarse granularity switching, a hybrid-switching optical router with combined OWS and electrical packet switching is a necessity in order to accommodate the entire multi-granularity traffic with multi-service requirements in a cost-effective manner. Its coordination capability of optical circuit switching and electrical packet switching enables efficient/intelligent usage of network resources. In this paper, we first review research and developments of such IP routers employing optical switching/interconnection techniques and examine how these techniques can be used inside routers to scale node capacity and to improve optical Internet performance. We also present and study the performance of a terabit optical router with an optical-electrical hybrid-switching fabric. The node architecture is based on the idea of IP over WDM integration with Generalized Multi-Protocol Label Switching (GMPLS). The network-level performance evaluations show that the proposed hybrid-switching optical router is a cost-effective solution for building the next generation GMPLS-based multi-granularity optical Internet.     

半导体光放大器的偏振光开关性能改进

半导体光放大器(SOA)非线性偏振旋转效应的光开关具有开关速度快、易集成等优点,其开关操作可以通过改变注入SOA中的电流而获得。这种偏振光开关的性能主要受注入光功率与控制电流的大小范围来决定。基于SOA中的偏振主态的概念,分析了非线性偏振旋转效应与控制电流的关系,并对不同功率的注入光进行了偏振旋转实验,分别实现了偏振光开关的操作。实验结果表明:随着注入光功率的增加可以提高光开关的分光比,有效改进光开关的性能。当注入光为5 dBm时,光开关的分光比与消光比均可达到30 dB。     

Efficient nearly-optimal motion and structure from images via analysis of dimensional reduction: application to safety checking system

In computing 3D motion and structure from image correspondences, often called the structure from motion (SFM) problem, dimensions of the used variable set are very large because it contains both motion and structure parameters. As a result, to solve the problem incurs much computational burden. However, in on-line applications of the SFM problem, computational efficiency needs to be stressed as some accuracy of the solutions is sacrificed. In this respect, various dimensional reduction methods are often introduced to improve computational efficiency and this usually leads to various reduced-form SFM problems. The so-obtained reduced-form SFM problems depend on fewer unknowns than the original SFM problem, thus allowing, in principle, for a less computationally intensive estimation, albeit potentially sacrificing accuracy of the results. It is thus interesting to study how much accuracy is lost. This is done by analytically proving results on equivalence or proximity of solutions for some example cases of the so-obtained reduced-form SFM problems. And then, based on the analysis, the author also proposes how to reduce the loss of accuracy in the reduced-form SFM problems (in the meaning of adjusting those reduced-form SFM problems to better approximate the original optimal SFM problem; that is, an optimal SFM problem that does not use any dimensional reduction methods). Experimental results are given to show the effect in practice. Finally, as an example application, a safety checking system using vision is considered.     

Optical packet switching: A reality check

This paper presents an analysis of the energy consumption in a number of optical switch fabric architectures for optical packet-switched applications and compares them to electronic switch fabrics. Optical packet switching does not appear to offer any substantial power consumption advantages over electronic packet switching. Therefore, there is no compelling case for optical packet switching.     

7-羟基喹啉二甲基亚砜溶液的光开关效应

研究了7羟基喹啉（7HQ）在二甲基亚砜（DMS）溶液中的全光光开关效应和激发态质子转移（ES-PT）效应。7HQ在与它能形成分子间氖键的溶剂中，在紫外光的激发下会发牛ESPT效应，使分子的构型发生变化，引起折射率也发生变化，是一种性能优良的全光光开关工作介质。DMS与7HQ不能形成分子间氢键，故7-HQ在DMS溶液中不能发生ESPT，不具有全光光开关效应。但实验发现，7-HQ的DMS溶液经强紫外光照射一段时间后出现了很强的光开关现象。比较了经强紫外光照射前后7-HQ的DMS溶液的吸收光谱和荧光光谱，报道了这一新现象并探讨了其产生的机理。     

Impacts of mismatched intrinsic parameter on leader-laggard synchronization between two mutually coupled VCSELs

Based on spin-flip model (SFM),the impacts of mismatched intrinsic parameter on leader-laggard chaos synchronization between two mutually coupled verticalcavity surface-emitting lasers (VCSELs) have been investigated numerically.Results show that,for two VCSELs with identical intrinsic parameter,the switching point of leader-laggard caused by continually varying frequency detuning or injection rate detuning is located at zero frequency detuning or zero injection rate detuning,which indicates that the VCSEL with higher frequency or subject to lower injection level plays a leader role.However,for two VCSELs with mismatched intrinsic parameter,the switched point of leader-laggard will deviate from zero frequency detuning or zero injection rate.Therefore,compared with the results obtained under matched intrinsic parameter,the opposite results have been observed in the range between zero detuning and switching point.Additionally,the offsets of switching point induced by different intrinsic parameters are different,and the influence of line-width enhancement factor is found to be the most significant.     

A new waveband switching method for reducing the number of ports in wavelength-division-multiplexing optical networks

In this paper, we investigate the waveband switching technique and consider the problem of reducing the number of ports in optical cross-connects in wavelength-division-multiplexing optical networks. The basic idea of waveband switching is to bind several wavelengths into one waveband which can be switched by only one port so that the switches in conventional wavelength routed networks can be reduced and the cost of optical cross-connects can be saved. Since the traditional waveband switching schemes are the simple shortest route approach and the obtained paths may not be the optimal disposals for merging waveband, we propose a new heuristic waveband switching routing method. In our proposed method, we use the k-shortest path algorithm and the rerouting approach to optimize the number of ports in optical cross-connects. Simulation results show that, compared with the traditional algorithm that does not consider the waveband switching technique, the performance improvement of our proposed method is significant and promising.     

Optical burst switching for service differentiation in thenext-generation optical Internet

In an effort to eliminate the electronic bottleneck, new optical switches/routers (hardware) are being built for the next-generation optical Internet where IP runs over an all-optical WDM layer. However, important issues yet to be addressed in terms of protocols (software) are how to develop a new paradigm that does not require any buffer at the WDM layer, as in circuit switching, and elimination of any layers between which exist mainly due to historical reasons. At the same time, such a paradigm should also efficiently support bursty traffic with high resource utilization as in packet switching. This article surveys design issues related to a new switching paradigm called optical burst switching, which achieves a balance between circuit and packet switching while avoiding their shortcomings. We describe how OBS can be applied to the next-generation optical Internet, and in particular how offset times and delayed reservation can help avoid the use of buffer, and support quality of service at the WDM layer