Research on highly nonlinear photonic bandgap fibers

Since thefirst photonic crystal fiber (PCF) wasfabri-cated by Knight J C and his colleagues[1]at 1996 ,thistype of fibers ,consisting of a central defect region sur-rounded by multiple air holes running alongits length,has been the subject of much interes…     

4/spl times/10 GHz mode-locked multiple-wavelength fiber laser

We demonstrate a four-wavelength 10-GHz mode-locked erbium-doped fiber laser, with wavelength spacings of 3.5-5 nm. Nearly transform-limited Gaussian pulses of 11- to 14-ps duration are measured and all wavelengths are synchronous.     

Wearable Sensors-Enabled Human–Machine Interaction Systems: From Design to Application

In comparison to traditional bulky and rigid electronic devices, the human–machine interaction (HMI) system with flexible and wearable components is an inevitable future trend. To achieve effective, intuitive, and seamless manipulation of high-performance wearable HMI systems, it is important to develop effective strategies for designing material microstructures on flexible sensors and electric devices with excellent mechanical flexibility and stretchability. The real-time acquisition of human physiology and surrounding signals through accurate and flexible sensors is the basis of wearable HMIs. Herein, the construction of a wearable HMI system that utilizes sensors, communication modes, and actuators is reviewed. The mechanisms and strategies for designing various flexible sensors based on different mechanisms are analyzed and discussed. The functional mechanism, material selection, and novel design strategies of each part are summarized in detail. The different communication modes in interactive systems and the manufacturing technology of soft machines are also introduced. Additionally, the most advanced applications of wearable HMI systems in intelligent identification and security, interactive controls for robots, augmented reality, and virtual reality have been highlighted. The review concludes with an overview of the remaining key challenges and several ideas regarding the further improvement of wearable HMI systems.     

On the integration of SIC and MIMO DoF for interference cancellation in wireless networks

Recent advances in MIMO degree-of-freedom (DoF) models allowed MIMO research to penetrate the networking community. Independent from MIMO, successive interference cancellation (SIC) is a powerful physical layer technique used in multi-user detection. Based on the understanding of the strengths and weaknesses of MIMO DoF and SIC, we propose to have DoF-based interference cancellation (IC) and SIC help each other so that (i) precious DoF resources can be conserved through the use of SIC and (ii) the stringent SINR threshold criteria can be met through the use of DoF-based IC. In this paper, we develop the necessary mathematical models to realize the two ideas in a multi-hop wireless network. Together with scheduling and routing constraints, we develop a cross-layer optimization framework with joint DoF IC and SIC. By applying the framework on a throughput maximization problem, we find that SIC and DoF IC can indeed work in harmony and achieve the two ideas that we propose.     

Gold Nanoparticles and g‐C3N4‐Intercalated Graphene Oxide Membrane for Recyclable Surface Enhanced Raman Scattering

Toxic organic pollutants in the aquatic environment cause severe threats to both humans and the global environment. Thus, the development of robust strategies for detection and removal of these organic pollutants is essential. For this purpose, a multifunctional and recyclable membrane by intercalating gold nanoparticles and graphitic carbon nitride into graphene oxide (GNPs/g‐C₃N₄/GO) is fabricated. The membranes exhibit not only superior surface enhanced Raman scattering (SERS) activity attributed to high preconcentration ability to analytes through π–π and electrostatic interactions, but also excellent catalytic activity due to the enhanced electron–hole separation efficiency. These outstanding properties allow the membrane to be used for highly sensitive detection of rhodamine 6G with a limit of detection of 5.0 × 10^?14m and self‐cleaning by photocatalytic degradation of the adsorbed analytes into inorganic small molecules, thus achieving recyclable SERS application. Furthermore, the excellent SERS activity of the membrane is demonstrated by detection of 4‐chlorophenol at less than nanomolar level and no significant SERS or catalytic activity loss was observed when reusability is tested. These results suggest that the GNPs/g‐C₃N₄/GO membrane provides a new strategy for eliminating traditional, single‐use SERS substrates, and expands practical SERS application to simultaneous detection and removal of environmental pollutants.     

Comparing Through-Silicon-Via (TSV) Void/Pinhole Defect Self-Test Methods

Three methods have been proposed to test Through-Silicon-Vias (TSV) electrically prior to 3D integration. These test methods are (1) sense amplification; (2) leakage current monitor; and (3) capacitance bridge methods. These tests are aimed at detecting one or both of two failure types, pin-holes and voids. The test circuits measure capacitance and leakage current of the TSVs, and generate a 1 bit pass/fail signal. The outputs are streamed out through a scan chain. The test time is 10 μs for the leakage test and the sense amplification methods, and is 15 μs for the capacitive bridge method. All these methods can be implemented for test-before-stacking, which will increase assembled yield. Resolution, power and area of these TSV test circuits were compared. The performance of each circuit was studied at PVT corners. The IMEC TSV technology was assumed, and the designs were simulated using the 32 nm predicted device model. Without any failure, the TSV capacitance’s mean value is 37 fF, and its leakage resistance is higher than 850 MΩ. With respect to 37 fF standard capacitance, resolution for the sense amplification method is 3.3 fF (8.9%); it is 0.16 fF (0.4%) for the capacitance bridge method. Although the capacitance bridge method has relatively better resolution, it takes 4x area and 10x power than the other two, and is also more sensitive to PVT variation. Resolution of the leakage current monitor method is 10 MΩ (1.1%) with respect to its threshold 850 MΩ, and use 42.5aJ power in normal case. Sense amplification circuit can be modified to detect equivalent leakage resistance under 2KΩ.     

放电泵浦XeCl激光的理论模型

本文对传输线作电源的自持放电XeCl激光进行动力学分析,给出电子能量分布玻尔兹曼方程、能量平衡方程、电子线路方程及激光振荡方程的数值解,并与实验结果作了比较。     

A network traffic prediction model of smart substation based on IGSA‐WNN

The network traffic prediction of a smart substation is key in strengthening its system security protection. To improve the performance of its traffic prediction, in this paper, we propose an improved gravitational search algorithm (IGSA), then introduce the IGSA into a wavelet neural network (WNN), iteratively optimize the initial connection weighting, scalability factor, and shift factor, and establish a smart substation network traffic prediction model based on the IGSA‐WNN. A comparative analysis of the experimental results shows that the performance of the IGSA‐WNN‐based prediction model further improves the convergence velocity and prediction accuracy, and that the proposed model solves the deficiency issues of the original WNN, such as slow convergence velocity and ease of falling into a locally optimal solution; thus, it is a better smart substation network traffic prediction model.     

一种动态利用码资源的CDMA系统性能研究

本文提出了一种基于随机预约ALOHA访问方式,能支持话音和数据业务的动态使用码资源的码分多址访问协议。在该协议中,话音终端采用预约请求排队访问方式。数据终端采用时隙ALOHA方式传输数据分组。理论分析和计算机仿真结果表明,该协议能有效地提高系统码资源的利用率。在系统处于重负载情况下该协议能优先保证话音业务服务质量,而处于轻负载下系统码资源能为数据业务充分使用。     

4H-SiC金属-半导体-金属结构紫外探测器的模拟与分析

用MEDICI软件对金属-半导体-金属(MSM)结构4H-SiC紫外(UV)探测器的I-V特性以及光谱响应等特性进行了模拟与分析,并探讨了金属电极的宽度、电极间距以及外延层厚度对探测器响应度的影响.结果表明,室温下该探测器的暗电流线性密度达到10-13A/μm,且在不同电压下光电流至少比暗电流大两个数量级;探测器的光谱响应范围为200~400 nm,在347 nm处响应度达到极大值;增大指宽或者减小指间距可以提高探测器的响应度;当波长小于峰值波长时外延层厚度对探测器的响应度基本没影响,而当波长大于峰值波长时随着外延层厚度的增大探测器的响应度有所增大.