多泵浦光纤拉曼放大器增益性能研究

FRA(光纤拉曼放大器)增益的峰值位置由泵浦波长决定,不同波长的泵浦光在不同的信号波长处产生最大增益。为获得最佳的FRA增益特性,采用多波长泵浦FRA理论模型,利用Optisystem软件建立了多泵浦FRA系统,通过系统仿真,研究了光纤通信系统中FRA的增益特性,分析了传输距离、纤芯有效面积、泵浦光功率和泵浦数量等因素对FRA增益的影响,确定了影响FRA增益的最佳参数,验证了FRA仿真系统的正确性和设计方案的可行性。     

高功率LD阵列侧面泵浦激光晶体的增益分布研究

研究了LD Bar侧面半环形直接泵浦Nd:YAG激光增益介质的泵浦光分布特点.建立了不同泵浦参数下棒状增益介质内的泵浦光能量分布数值模型,通过光线追迹方法,并利用Matlab软件进行了数值模拟计算,分析了几个泵浦参数对泵浦光分布的影响,总结了一般的影响规律,分析了产生差异的原因,提出了选取泵浦参数时需注意的问题.可为激光二极管环绕泵浦固体激光器的泵浦结构设计提供理论上的指导.     

高功率固体激光放大器中增益均匀化研究

针对高功率固体激光放大器中增益分布不均匀的现象,为获得较为均匀的增益分布,提出了分布式泵浦的方法.相对于均匀泵浦,分布式泵浦就是通过设计使得泵浦场具有一定的分布.在总体泵浦功率相同的情况下,分别对均匀泵浦和一定分布的分布式泵浦条件下产生的增益分布进行了模拟计算.结果表明,与均匀泵浦相比,使用分布式泵浦方法获得了较为均匀...     

基于粒子群优化算法的双向多泵浦光纤拉曼放大器增益研究

基于石英光纤作为增益介质,采用龙格-库塔法、打靶法求解多波长双向泵浦光纤拉曼放大器的功率耦合波方程,得到拉曼放大器的增益带宽,平均增益,增益平坦度以及泵浦光和信号光沿光纤的分布。再通过粒子群优化算法对同一数量泵浦光不同排列双向系统进行逐个优化分析,在14种双向泵浦结构中选出性能较优的三种结构,再对它们优化参数设置,最终得到性能最优的双向泵浦结构BBFF。研究结果表明:在仅有四个泵浦光的情况下,双向多泵浦结构BBFF具有最优的平均增益和增益平坦度,并且得到了开关增益为23.1665 dB,增益平坦度为0.794 dB的双向泵浦结构。     

多泵浦喇曼放大器的增益特性分析

提出了用同向泵浦的剩余泵浦功率作为反向泵浦的泵浦功率迭代初值,用Lorentz线型拟合喇曼增益系数,采用简明的数学模型,对比分析了同向、反向多波长泵浦喇曼放大器的增益特性以及信号间的受激喇曼散射对增益的影响.     

宽带拉曼光纤放大中的多泵浦源选择方法

理论分析了拉曼光纤放大谱与多波长泵浦光功率和波长的关系.考虑到泵浦光与泵浦光,泵浦光与信号光的拉曼相互作用,得出一个增益数组,增益数组就是离散的宽带拉曼光纤放大增益谱.对任何形态的宽带拉曼光纤放大增益谱,可以设定对应的增益数组,把泵浦光功率和波长组成二维坐标系,遍取坐标系中的各点,求出各组点对应的增益数组,找出最接近设定的增益数组,这组泵浦光功率及波长就是最优的解决方案.     

多泵浦增益平坦光子晶体拉曼光纤放大器

针对密集波分复用光纤通信系统中拉曼光纤放大器增益及增益谱平坦问题,提出一种采用4个泵浦光的多泵浦方式在光子晶体光纤不同位置处注入两种不同波长泵浦光的组合方式来获得拉曼光纤放大器增益更大、增益谱更加平坦的方法。这种组合方式在拉曼光纤放大器中使得光信号实现了前段放大、后段补偿,从而在拉曼光纤放大器输出端获得高增益和较平坦增益谱。模拟的结果表明:平均增益可达:26.5 dB,增益平坦度为0.046 dB。     

拉曼光纤放大器的一种简化模型

提出了一种多泵浦反向光纤拉曼放大器（FRA）的新型实用模型，能够给出小信号增益和噪声指数。采用数值计算泵浦光的传播规律，利用此结果解析求解信号光沿光纤的功率演化，解决了泵浦与信号光反向传输的问题。利用拟合图谱通过插值得到拉曼增益系数代替传统的将拉曼增益谱近似为三角形的方法。模型中考虑了泵浦与泵浦、泵浦与信号之间的相互作用，并包含自发拉曼散射噪声。     

多波长光纤喇曼放大器及其泵浦优化

密集波分复用(DWDM)的发展对放大器的要求越来越高,多波长光纤喇曼放大器(MW-FRA)解决了放大带宽的问题,但由于多泵浦喇曼放大过程的复杂性,很难控制增益谱线的平坦度。文章分析了MW-FRA的泵浦和信号功率耦合方程,推导出增益表达式。比较了两种优化算法的优劣,并使用遗传算法对泵浦进行了优化。获得了较平坦的增益谱。     

侧面折返泵浦多边形Nd∶YAG薄片的热效应研究

针对热效应劣化激光光束质量、限制激光功率水平提升的问题,研究了激光二极管侧面折返泵浦的多边形Nd∶YAG的热效应,进行了有限元数值模拟计算和实验研究。对于侧面90°切割和45°切割的两种多边形薄片增益介质,对比分析了在侧面泵浦方式下,介质轴向及径向的泵浦光吸收功率分布和温度分布。实验测量了侧面折返泵浦模式下,45°切割的增益介质的荧光分布、温度分布和热致波前畸变,实验结果与理论分析吻合。研究表明,侧面折返泵浦的45°切割多边形薄片增益介质有利于实现储能近平顶分布,并进一步降低增益介质的热效应。     

Effective Capacity-Based Quality of Service Measures for Wireless Networks

An important objective of next-generation wireless networks is to provide quality of service (QoS) guarantees. This requires a simple and efficient wireless channel model that can easily translate into connection-level QoS measures such as data rate, delay and delay-violation probability. To achieve this, in Wu and Negi (IEEE Trans. on Wireless Communications 2(4) (2003) 630–643), we developed a link-layer channel model termed effective capacity, for the setting of a single hop, constant-bit-rate arrivals, fluid traffic, and wireless channels with negligible propagation delay. In this paper, we apply the effective capacity technique to deriving QoS measures for more general situations, namely, (1) networks with multiple wireless links, (2) variable-bit-rate sources, (3) packetized traffic, and (4) wireless channels with non-negligible propagation delay. Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. From July 1997 to December 1999, he conducted graduate research at Polytechnic University, Brooklyn, New York. During the summers of 1998, 1999 and 2000, he conducted research at Fujitsu Laboratories of America, Sunnyvale, California, on architectures and traffic management algorithms in the Internet and wireless networks for multimedia applications. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001. Currently, he is an Associate Editor for the IEEE Transactions on Vehicular Technology and Associate Editor for International Journal of Ad Hoc and Ubiquitous Computing. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as TPC member of over 20 conferences such as IEEE INFOCOM'05, IEEE ICC'05, IEEE WCNC'05, and IEEE Globecom'04. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. He is also Director of Communications, IEEE Gainesville Section. Rohit Negi received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, India in 1995. He received the M.S. and Ph.D. degrees from Stanford University, CA, USA, in 1996 and 2000 respectively, both in Electrical Engineering. He has received the President of India Gold medal in 1995. Since 2000, he has been with the Electrical and Computer Engineering department at Carnegie Mellon University, Pittsburgh, PA, USA, where he is an Assistant Professor. His research interests include signal processing, coding for communications systems, information theory, networking, cross-layer optimization and sensor networks.     

Performance of Multilayered Video Encoding and Delivery over Lossy Channels Using a Joint Source-Channel Coding Approach

In this paper, the performance of selected error-control schemes based on forward error-control (FEC) coding for H.263+ video transmission over an additive white Gaussian noise (AWGN) channel is studied. Joint source and channel coding (JSCC) techniques that employ single-layer and 2-layer H.263+ coding in conjunction with unequal error protection (UEP) to combat channel errors are quantitatively compared. Results indicate that with appropriate joint source and channel coding, tailored to the respective layers, FEC-based error control in combination with 2-layer video coding techniques can lead to more acceptable quality for wireless video delivery in the presence of channel impairments. Yong Pei is currently a tenure-track assistant professor in the Computer Science and Engineering Department, Wright State University, Dayton, OH. Previously he was a visiting assistant professor in the Electrical and Computer Engineering Department, University of Miami, Coral Gables, FL. He received his B.S. degree in electrical power engineering from Tsinghua University, Beijing, in 1996, and M.S. and Ph.D. degrees in electrical engineering from Rensselaer Polytechnic Institute, Troy, NY, in 1999 and 2002, respectively. His research interests include information theory, wireless communication systems and networks, and image/video compression and communications. He is a member of IEEE and ACM. James W. Modestino (S′67- M′73- SM′81- F′87) was born in Boston, MA, on April 27, 1940. He received the B.S. degree from Northeastern University, Boston, MA, in 1962, and the M.S. degree from the University of Pennsylvania, Philadelphia, PA, in 1964, both in electrical engineering. He also received the M.A. and Ph.D. degrees from Princeton University, Princeton, NJ, in 1968 and 1969, respectively. He has held a number of industrial positions, including positions with RCA Communications Systems Division, Camden, NJ; General Electronic Laboratories, Cambridge, MA; AVCO Systems Division, Wilmington, MA; GTE Laboratories, Waltham, MA; and MIT Lincoln Laboratories, Lexington, MA. From 1970 to 1972, he was an Assistant Professor in the Department of Electrical Engineering, Northeastern University. In 1972, he joined Rensselaer Polytechnic Institute, Troy, NY, where until leaving in 2002 he was an Institute Professor in the Electrical, Computer and Systems Engineering Department and Director of the Center for Image Processing Research. He has been responsible for teaching and research in the communication, information and signal processing systems area. His specific research interests include communication in fading dispersive channels; detection, estimation and filtering in impulsive or burst noise environments; digital signal, image and video processing; and multimedia communication systems and networks. In 2002 he joined the Department of Electrical and Computer Engineering at the University of Miami, Coral Gables, FL, as the Victor E. Clarke Endowed Scholar, Professor and Chair. He has held visiting positions with the University of California at San Diego, LaJolla, CA (1981–1982); GE Research and Development Center, Schenectady, NY (1988–1989); and Massachusetts Institute of Technology, Cambridge, MA (1995–1996). Dr. Modestino is a past member of the Board of Governors of the IEEE Information Theory Group. He is a past Associate Editor and Book Review Editor for the IEEE TRANSACTIONS ON INFORMATION THEORY. In 1984, he was co-recipient of the Stephen O. Rice Prize Paper Award from the IEEE Communications Society and in 2000 he was co-recipient of the best paper award at the International Packet Video Conference.     

Comments on “A Class of Fault-Tolerant Multiprocessor Networks”

A. Ghafoor presented node-disjoint paths of even networks using Figs. 4, 5, 6,and 7 (Ghafoor, IEEE Trans. Reliability, vol. 38, no. 1, pp. 5-15). However, the paper contains errors which cause confusion. We show that the node-disjoint paths, and Theorem 4 (Ghafoor, IEEE Trans. Reliability, vol. 38, no. 1, pp. 5-15), are not correct. We propose advanced node-disjoint paths, and prove that the fault diameter of even networks is d+1. This is optimal.     

Exploring the potential of Siamese network for RGBT object tracking

Siamese tracking is one of the most promising object tracking methods today due to its balance of performance and speed. However, it still performs poorly when faced with some challenges such as low light or extreme weather. This is caused by the inherent limitations of visible images, and a common way to cope with it is to introduce infrared data as an aid to improve the robustness of tracking. However, most of the existing RGBT trackers are variants of MDNet (Hyeonseob Nam and Bohyung Han, Learning multi-domain convolutional neural networks for visual tracking, in: Proceedings of the IEEE conference on computer vision and pattern recognition, 2016, pp. 4293–4302.), which have significant limitations in terms of operational efficiency. On the contrary, the potential of Siamese tracking in the field of RGBT tracking has not been effectively exploited due to the reliance on large-scale training data. To solve this dilemma, in this paper, we propose an end-to-end Siamese RGBT tracking framework that is based on cross-modal feature enhancement and self-attention (SiamFEA). We draw on the idea of migration learning and employ local fine-tuning to reduce the dependence on large-scale RGBT data and verify the feasibility of this approach, and then we propose a reliable fusion approach to efficiently fuse the features of different modalities. Specifically, we first propose a cross-modal feature enhancement module to exploit the complementary properties of dual-modality, followed by capturing non-local attention in channel and spatial dimensions for adaptive weighted fusion, respectively. Our network was trained end-to-end on the LasHeR (Chenglong Li, Wanlin Xue, Yaqing Jia, Zhichen Qu, Bin Luo, Jin Tang, LasHeR: A Large-scale High-diversity Benchmark for RGBT Tracking, CoRR abs/2104.13202, 2021) training set and reached new SOTAs on GTOT (C. Li, H. Cheng, S. Hu, X. Liu, J. Tang, L. Lin, Learning collaborative sparse representation for grayscale-thermal tracking, IEEE Trans. Image Process, 25 (12) (2016) 5743–5756.), RGBT234 (C. Li, X. Liang, Y. Lu, N. Zhao, and J. Tang, “Rgb-t object tracking: Benchmark and baseline,” Pattern Recognition, vol. 96, p. 106977, 2019.), and LasHeR (Chenglong Li, Wanlin Xue, Yaqing Jia, Zhichen Qu, Bin Luo, Jin Tang, LasHeR: A Large-scale High-diversity Benchmark for RGBT Tracking, CoRR abs/2104.13202, 2021) while running in real-time.     

Automatic calibration of Hall sensor microsystems

In many applications, a Hall element is used for contact-less measurement such as linear and angular positions, electrical current, power and energy, etc. The Hall element fabricated by means of CMOS technology features mediocre characteristics [R.S. Popovic, Z. Randjelovic, D. Manic, Integrated Hall-Effect Magnetic Sensors, EMSA, Germany, 2000; R.S. Popovic, Hall Effect Devices, Adam Hilger, Bristol, Philadelphia, New York, 1991]. It gives a weak output signal of the order of a few mV. This signal is often corrupted by sensor offset, noise, temperature and aging drift. This paper deals with the state of the art and main techniques capable to detect and compensate these issues. Case studies using mentioned techniques are also summarized.     

A six-channel wavelength multiplexer and demultiplexer for single mode systems

We have fabricated and evaluated the first single mode wavelength multiplexer based on a diffraction grating and strip waveguides. The waveguides were employed to minimize the physical spacing between inputs in order to maximize the ratio of channel width to channel separation. The center channel insertion losses for the six channel device were 6.4, 4.9, 6.0, 5.6, 6.8, and 7.8 dB at 1279, 1308, 1338, 1508, 1536, and 1566 nm, respectively. The 1-dB full channel widths averaged 6.0 nm. A matching demultiplexer with multi-mode outputs was also fabricated. The center channel insertion losses were 0.9, 1.1, 1.2, 1.7, 1.8, and 2.1 dB at 1278, 1310, 1337, 1505, 1533, and 1563 nm, respectively. Full 1-dB channel widths ranged from 15 to 11 nm. Out of band rejection exceeded 35 dB.     

X-ray metrology for high-k atomic layer deposited HfxZr1−xO2 films

Hafnium-based dielectrics are the most promising material for SiO₂ replacement in future nodes of CMOS technology. While devices that utilize HfO₂ gate dielectrics suffer from lower carrier mobility and degraded reliability, our group has recently reported improved device characteristics with a modified Hf_xZr_1−xO₂ [R.I. Hegde, D.H. Triyoso, P.J. Tobin, S. Kalpat, M.E. Ramon, H.-H. Tseng, J.K. Schaeffer, E. Luckowski, W.J. Taylor, C.C. Capasso, D.C. Gilmer, M. Moosa, A. Haggag, M. Raymond, D. Roan, J. Nguyen, L.B. La, E. Hebert, R. Cotton, X.-D. Wang, S. Zollner, R. Gregory, D. Werho, R.S. Rai, L. Fonseca, M. Stoker, C. Tracy, B.W. Chan, Y.H. Chiu, B.E. White, Jr., in: Technical Digest - International Electron Devices Meet, vol. 39, 2005, D.H. Triyoso, R.I. Hegde, J.K. Schaeffer, D. Roan, P.J. Tobin, S.B. Samavedam, B.E. White, Jr., R. Gregory, X.-D. Wang, Appl. Phys. Lett. 88 (2006) 222901]. These results have lead to evaluation of X-ray reflectivity (XRR) for monitoring high-k film thickness and control of Zr addition to HfO₂ using measured film density. In addition, a combination of XRR and spectroscopic ellipsometry (SE) is shown to be a fast and non-intrusive method to monitor thickness of interfacial layer between high-k and the Si substrate.     

Test of switched-capacitor ladder filters using OBT

In this paper, a way to test switched-capacitors ladder filters by means of Oscillation-Based Test (OBT) methodology is proposed. Third-order low-pass Butterworth and Elliptic filters are considered in order to prove the feasibility of the proposed approach. A topology with a non-linear element in an additional feedback loop is employed for converting the Circuit Under Test (CUT) into an oscillator. The idea is inspired in some author's previous works (G. Huertas, D. Vázquez, A. Rueda, J.L. Huertas, Oscillation-based Test Experiments in Filters: a DTMF example, in: Proceedings of the International Mixed-Signal Testing Workshop (IMSTW'99), British Columbia, Canada, 1999, pp. 249–254; G. Huertas, D. Vazquez, E. Peralías, A. Rueda, J.L. Huertas, Oscillation-based test in oversampling A/D converters, Microelectronic Journal 33(10) (2002) 799–806; G. Huertas, D. Vázquez, E. Peralías, A. Rueda. J.L. Huertas, Oscillation-based test in bandpass oversampled A/D converters, in: Proceedings of the International Mixed-Signal Test Workshop, June 2002, Montreaux (Switzerland), pp. 39–48; G. Huertas, D. Vázquez, A. Rueda, J.L. Huertas, Practical oscillation-based test of integrated filters, IEEE Design and Test of Computers 19(6) (2002) 64–72; G. Huertas, D. Vázquez, E. Peralías, A. Rueda, J.L. Huertas, Testing mixed-signal cores: practical oscillation-based test in an analog macrocell, IEEE Design and Test of Computers 19(6) (2002) 73–82). Two methods are used, the describing function approach for the treatment of the non linearity and the root-locus method for analysing the circuit and predicting the oscillation frequency and the oscillation amplitude. In order to establish the accuracy of these predictions, the oscillators have been implemented in SWITCAP (K. Suyama, S.C. Fang, Users' Manual for SWITCAP2 Version 1.1, Columbia University, New York, 1992). Results of a catastrophic fault injection in switches and capacitors of the filter structure are reported. A specification-driven fault list for capacitors is also defined based on the sensitivity analysis. The ability of OBT for detecting this kind of faults is presented.     

A Virtual MAC Address Scheme for Mobile Ethernet

Heterogeneous wireless access is being integrated into IP networks to support future wireless systems. The enhanced IP technologies being developed must address both handover issues related to mobility management and security issues related to wireless access. We previously proposed a network architecture, Mobile Ethernet, based on wide area Ethernet technologies, that reduces overhead involving handover by managing mobility in the IEEE802 MAC layer. We also proposed a virtual MAC address scheme that introduces a host identifier into layer 2 to accommodate heterogeneous wireless access, manage handover between wireless accesses, provide scalability, and ensure security. In this paper, we design the virtual MAC address scheme for Mobile Ethernet and describe the sequence diagrams of the scheme. We also clarify the effect of our proposed scheme from the viewpoint of scalability by comparing the simulated signaling traffic load at handover with that using FMIPv6. Yoshia Saito received his B.E. and M.E. degrees from Shizuoka University, Shizuoka, Japan, in 2002 and 2003 respectively. He is currently a student in Ph.D. course in the university. From January 2004, he is also working as a visiting researcher at National Institute of Information and Communications Technology, Yokosuka, Japan. His research interests include mobile computing and next generation wireless systems. Masahiro Kuroda received the M.E. degree in systems science from the Tokyo Institute of Technology, Japan, in 1980, the M.S. degree in computer science from University of California, Santa Barbara, CA, in 1989, and received the Ph.D. degree in computer science from Shizuoka University, Japan, in 2000. He joined Mitsubishi Electric Corporation, Kamakura, Japan in 1980. Since then, he was engaged in OS/network developments, mobile network computing R&D, and cellular Java standardizations. He is currently working as a group leader at National Institute of Information and Communications Technology, Yokosuka, Japan. His current research interests includes wireless network, wireless security, mobile systems, ubiquitous systems, and next generation wireless systems architecture. He is a member of the IEEE Computer Society. Tadanori Mizuno received the B.E. degree in industrial engineering from the Nagoya Institute of Technology in 1968 and received the Ph.D. degree in computer science from Kyushu University, Japan, in 1987. In 1968, he joined Mitsubishi Electric Corp. Since 1993, he is a Professor of Faculty of Engineering, Shizuoka University, Japan. He moved to the Faculty of Information, Shizuoka University in 1995. His research interests include mobile computing, distributed computing, computer networks, broadcast communication and computing, and protocol engineering. He is a member of Information Processing Society of Japan, the institute of electronics, information and Communication Engineers, the IEEE Computer Society and ACM.     

Characterisation of electroplated Sn/Ag solder bumps

Environmental concerns as well as legal constraints have been pushing research on flip chip technology towards the development of lead-free solders and also to new deposition techniques [Z.S. Karim, R. Schetty, Lead-free bump interconnections for flip-chip applications, in: IEEE/CPMT 1nternational Electronics Manufacturing Technology Symposium, 2000, pp. 274-278, P. Wölflick, K. Feldmann, Lead-free low-cost flip chip process chain: layout, process, reliability, in: IEEE International Electronics Manufacturing Technology (IEMT) Symposium, 2002, pp. 27-34, M. McCormack, S. Jin, The design and properties of new, pb-free solder alloys, in: IEEE/CPMT International Electronics Manufacturing Technology Symposium, 1994, pp. 7-14, T. Laine-Ylijoki, H. Steen, A. Forsten, Development and validation of a lead-free alloy for solder paste applications. IEEE Transactions on Components, Packaging, and Manufacturing technology, 20(3) (1997) 194-198, D. Frear, J. Jang, J. Lin, C. Zhang, Pb-free solders for flip-chip interconnects, JOM, 53(6) (2001) 28-32].Binary and ternary tin alloys are promising candidates to substitute lead-content components. In this paper, we describe an electroplating technique for high density FlipChip packaging [M. Bigas, E. Cabruja, Electrodeposited Sn/Ag for flip chip connection, CDE (2003)]. An analysis using Auger Electron Spectroscopy (AES) together with additional Energy Dispersive Xray analysis (EDS) tests and Scanning Electron Microscope (SEM) analysis have been performed to optimize the reflow process of the electrodeposited bumps.