太赫兹波导发展现状与展望

太赫兹波具有良好的穿透性、低能性和宽带性,在高速空间通信、环境监测、外差探测、医学探测、无损检测和国防安全等领域具有重要的应用前景。波导传输技术和功能器件是太赫兹系统不可或缺的重要组成部分,太赫兹波导的性能决定了太赫兹系统的信号传输效率和集成度,引起人们的研究兴趣。近年来,太赫兹波导的发展取得了长足的进步,从普通的金属空心波导到金属线波导、介质光纤,再到最近的人工表面等离激元波导、石墨烯、铌酸锂等新型波导,它们展现出了各自的优势,令人振奋。该综述全面介绍了太赫兹波导领域的发展及研究近况,并对其未来应用进行了展望。     

太赫兹成像技术用于皮肤烧伤检测的研究进展

随着太赫兹(0.1~10 THz)光谱技术的快速发展,太赫兹成像开始应用于生物医学等领域,尤其是应用于皮肤烧伤检测中,但如何将这一技术从实验室研究转向实际临床检测还面临着巨大挑战。太赫兹技术在皮肤烧伤程度评估领域已经得到了较为深入的研究,包括成像系统、离体实验和活体实验研究等,得到了较为清晰的太赫兹图像。首先概述了皮肤烧伤程度分类方法和现有诊断方法,然后介绍太赫兹成像应用于皮肤烧伤评估的研究进展,本文重点从成像系统、检测结果和烧伤程度评估方法三个方面进一步说明了其研究进展和不足,最后提出了面向皮肤烧伤临床检测的太赫兹成像发展趋势和需要解决的问题。     

THz射线产生技术及应用最新进展

THz电磁脉冲是由超短激光脉冲选通半导体光导开关后产生的超宽频带电磁辐射,在很多基础研究领域、工业应用领域以及军事领域中有相当重要的应用。作者就THz电磁脉冲的产生技术、探测技术作了较全面的评述。对其若干重要应用研究成果包括THz时域光谱技术(TDS)、THz二维成像技术等也进行了分析。     

Recent advances of nanolead-free solder material for low processing temperature interconnect applications

Recent advances of nanolead-free solder materials for microelectronic packaging is presented. The syntheses of Sn, SnAg and SnAgCu nanoparticles and their size dependent melting temperature are discussed. Capping nanoparticle surfaces with organic molecules for antioxidation and particle size control is studied as well. An in-house made nanosolder pastes is formulated and its metallurgical joint onto a Cu substrate is demonstrated.     

Non-linear graphene optics for terahertz applications

The linear electrodynamic properties of graphene—the frequency-dependent conductivity, the transmission spectra and collective excitations—are briefly outlined. The non-linear frequency multiplication effects in graphene are studied, taking into account the influence of the self-consistent-field effects and of the magnetic field. The predicted phenomena can be used for creation of new devices for microwave and terahertz optics and electronics.     

Recent advances in optoelectronic properties and applications of two-dimensional metal chalcogenides

Since two-dimensional (2D) graphene was fabricated successfully, many kinds of graphene-like 2D materials have attracted extensive attention. Among them, the studies of 2D metal chalcogenides have become the focus of intense research due to their unique physical properties and promising applications. Here, we review significant recent advances in optoelectronic properties and applications of 2D metal chalcogenides. This review highlights the recent progress of synthesis, characterization and isolation of single and few layer metal chalcogenides nanosheets. Moreover, we also focus on the recent important progress of electronic, optical properties and optoelectronic devices of 2D metal chalcogenides. Additionally, the theoretical model and understanding on the band structures, optical properties and related physical mechanism are also reviewed. Finally, we give some personal perspectives on potential research problems in the optoelectronic characteristics of 2D metal chalcogenides and related device applications.     

Recent advances in theory and applications of scrambling techniquesfor lightwave transmission

This paper discusses recent advances in the theory and applications of scrambling techniques for digital lightwave transmission. It introduces the theories of sequence space and shift register generator (SRG) space which enable systematic analysis and mathematical manipulation of the behavior of sequences in general and the related SRG's. It discusses the behavior and realization of frame synchronous scrambling (FSS) and distributed sample scrambling (DSS) with emphasis on parallel sequences and the related parallel SRG's (PSRG). In addition, it describes self synchronous scrambling (SSS). Then the paper applies the theories to today's lightwave transmission systems by demonstrating practical parallel designs of FSS for SDH/SONET transmission, DSS for cell-based ATM transmission, and SSS for SDH-based ATM transmission. It finally considers how DSS can be used for scrambling of mixed isochronous and nonisochronous data in future high-speed data networks. The paper employs various new concepts and terminology, such as PSRG engine, generating vector discrimination matrix, (M,N) PSRG, sampling vector, correction vector, correction matrix, predictable scrambling concurrent sampling, and immediate correction     

Recent advances in electro-optic devices,components and system for microwave and millimetre-wave applications

Basic characteristics, performances and designs of integrated optic devices and components for use in microwave and millimetre-wave applications and various techniques for the microwave control of optical devices are reviewed. In particular, methods of improving their performances and/or limitations of such devices and components are discussed. The prospects for these new technologies including recommendations for future work which are relevant to microwave and millimetre-wave systems are identified. This paper will include the following:

?Semiconductor Laser Diode Sources

?Photodetectors

?Direct Current Modulation of Laser Diodes

?Externally Modulated Fibre-Optic Link

?Applications of Fibre-Optic Links and Fibre Loop Memory

?Delay Line Signal Processing

     

高迁移率ZnO纳米线的太赫兹探测器应用

报道了一种使用氧化物纳米线(ZnO)构建的新型太赫兹探测器。首先合成了高品质的ZnO纳米线,并且以此制备了场效应管。通过电输运测量得出ZnO纳米线具有高的开关比和良好的场效应迁移率,因此ZnO纳米线可作为基于一维场效应管模型的太赫兹探测器的感应端。在室温下不同强度的入射太赫兹波(0.3 THz)都可引起光电压。此外,进一步的分析证明太赫兹波的光敏效应是由于ZnO样品自身的高迁移率引起的,这也说明了氧化物纳米电子学将在太赫兹领域得到更广阔的应用。     

面向太赫兹应用的InP基肖特基二极管

Based on characteristics such as low barrier and high electron mobility of lattice matched In_0.53Ga_0.47 As layer,InP-based Schottky barrier diodes（SBDs） exhibit the superiorities in achieving a lower turn-on voltage and series resistance in comparison with GaAs ones.Planar InP-based SBDs have been developed in this paper.Measurements show that a low forward turn-on voltage of less than 0.2 V and a cutoff frequency of up to 3.4 THz have been achieved.The key factors of the diode such as series resistance and the zero-biased junction capacitance are measured to be 3.32Ωand 9.1 fF,respectively.They are highly consistent with the calculated values.The performances of the InP-based SBDs in this work,such as low noise and low loss,are promising for applications in the terahertz mixer,multiplier and detector circuits.     

Complex permittivity characterization of benzocyclobutene for terahertz applications

High-quality polymers such as the benzocyclobutene polymer (BCB) provide interesting dielectric feature for terahertz applications. Already used in silicon integrated circuit technologies, this material could become one of the most promising candidates for the realization of future THz waveguides and interconnections on a silicon substrate but also after active devices process on the top of any other technology (GaAs, InP, GaN…). A frequency-dependent complex permittivity of spin-coated thick layers of this low-k dielectric is obtained from transmittance spectra measured with Fourier transform spectroscopy in the frequency range of 0.5-5.4 THz. The dielectric constant and the loss tangent are discussed according to curing conditions of the photosensitive resin used. A low loss tangent value of 7 − 9 × 10^-3 at 1 THz is obtained with polymerisation in oxygen-free atmosphere. An incomplete curing and a high dose UV exposure have a weak impact on losses. These results associated with the high compatibility of this polymer with silicon and metals make BCB layers well suited for the design of microelectronic THz devices and circuits.     

基于石墨烯的太赫兹光电功能器件研究进展

作为一种新型光电材料,石墨烯独特的能带结构和电子输运特性,使其与太赫兹科学有着密切的内在关系：石墨烯内部的等离子体振荡频率在太赫兹频段;人为调谐石墨烯的禁带宽度在0~0.3 eV时,正好覆盖太赫兹频段;光电导率的外部可控性等,这些特点使得石墨烯有望成为太赫兹频段新一代高性能设备研制的基础。最近的研究显示,石墨烯在太赫兹波产生、调控、检测等光电功能器件的研制中取得了很好的成果。重点介绍了基于石墨烯的太赫兹光电功能器件,包括太赫兹源器件、可控调控器件及检测器研究的最新进展,并对这一快速发展的研究领域进行了展望。     

Elliptical hollow core tube lattice fibers for terahertz applications

Hollow core microstructured fibers whose cladding is composed by an elliptical arrangement of circular dielectric tubes are numerically investigated. Birefringence, differential group delay, and polarization dependent loss are evaluated for different values of ellipticity in order to quantify its effect on the two polarizations of the fundamental core mode. All these parameters have a minimum at the center of each transmission window and they assume maximum values at the edges. In particular, the birefringence goes always to zero irrespective of ellipticity. This proves that tube lattice fibers are strongly immune against unwanted core shape deformation, in particular when the working frequency is close to the center of the transmission windows. On the other hand they are not suitable to obtain polarization maintaining fibers.     

应用于极紫外光刻系统多层膜的研究进展

极紫外光刻是采用波长为13.5nm的极紫外光作为光源,实现半导体集成电路工艺22纳米以及更窄线宽节点的主要候选光刻技术。性能优越稳定的多层膜技术是构建整个极紫外光刻系统的重要技术之一。从高反射率,波长匹配,控制面形以及稳定性和寿命方面总结了极紫外光刻系统中多层膜的性能要求和最新的研究进展,叙述了制备高性能多层膜的方法和沉积设备,讨论了多层膜制备技术还存在的问题和发展的方向。     

Recent advances in process synthesis for semiconductor devices

Recently, work has been started on a new methodology, called process synthesis, that has the potential to revolutionize integrated circuit (IC) process design in the same way that ASIC and microelectronics manufacturing science and technology (MMST) revolutionized circuit design and factory operation. This paper provides an overview of process synthesis, discusses synthesis methodologies, potential roadblocks to execution of this strategy, and presents recent progress in developing this capability     

Recent advances in fuzzy techniques for image enhancement

With the continued growth of multimedia and communications systems, the instrumentation and measurement fields have seen a steady increase in the focus on image data. Developing tools and techniques to enhance the quality of image data plays a very relevant role. Enhancement of noisy images, however, is not a trivial task. The filtering action should distinguish between unwanted noise (to be removed) and image details (to be preserved or possibly enhanced). Nonlinear filters based on fuzzy systems effectively complete this task, outperforming conventional methods. Fuzzy reasoning is very well suited to model the uncertainty that typically occurs when both noise cancellation and detail preservation represent very critical issues. Since 1992, the number of different approaches to fuzzy filtering has been progressively increasing. The goal of this article is to explain the basic principles of fuzzy filtering, focusing on a selection of the most significant methods     

Recent advances in rate control for video coding

In this paper, we review the recent advances in rate control techniques for video coding. The rate control algorithms recommended in the video coding standards are briefly described and analyzed. Recent advances, such as new concepts in rate-distortion modelling and quality constrained control, are presented. With these techniques, the rate control performance can be improved. The paper not only summarizes these recent rate control techniques but also provides explicit directions for future rate control algorithm design.     

Recent advances in solid electrolytes for synaptic transistors

Traditional computer development based on the Von Neumann system has encountered a bottleneck. The development of a brain-like computer that simulates the operation mode of the human brain is an important way to break the bottleneck. The high-performance multi-terminal synaptic transistor is the basic unit to realize a brain-like computer. In the multi-terminal synaptic transistor, electrolyte with electric double layer is the pivotal structure to realize the function of simulated synapse. Compared with ionic liquid and ionic gels,solid electrolytes have more stable chemical properties, and lower production costs. This article reviews the applications of these types of solid electrolytes in synaptic transistors. The content is mainly divided into four parts: organic solid electrolyte, inorganic solid electrolyte, organic-inorganic hybrid solid electrolyte, synaptic transistor application and future prospect. In this paper, the advantages and disadvantages of each material are summarized and compared, and various synaptic characteristics are analyzed in detail. This review has a good reference value for the study of solid electrolyte synaptic transistors.     

Recent advances in magnetic resonance

The author describes some advances in magnetic resonance imaging which have been made in approximately the last two years. These are in general areas of improved speed of image acquisitions, improved spatial resolution, selective imaging of blood vessels, and reduction of image artifact