光电振荡器的相位噪声特性

与传统的微波振荡器相比,光电振荡器利用光纤储能,能够产生低相位噪声的微波信号.论述了光电振荡器的特点、基本结构和工作原理,推导了相位噪声的表达式,对其特性进行了理论研究,并构建了光电振荡器的实验.理论分析表明,光纤延时、激光器的相对强度噪声以及微波放大器的噪声系数会影响光电振荡器的相位噪声,为减小相位噪声提供了理论依据.实验测量了3种光纤延时下的相位噪声,并与理论分析的结果进行了对比,证明了理论分析的正确性.     

基于光纤环选频特性的双环结构光电振荡器

提出并验证了一种借助于光纤环的选频特性实现辅助滤波的光电振荡器,利用偏振分束器(PBS)和偏振合束器(PBC)构成的双环路结构抑制掉部分光电振荡器的边模,同时借助于光纤环的光学梳状频率特性,对振荡器环路中的光信号模式再次进行选择,既起到边模抑制的作用,又提高了光电振荡器谐振腔的Q值.仿真结果表明:采用光纤环辅助滤波有利于光电振荡器的边摸抑制和单模输出,在保证光电振荡器输出低相位噪声和高频谱纯度微波信号的情况下,边模抑制比超过160 dB,模式间隔达到370 MHz,降低了对电域带通滤波器的性能要求,是一种新的光电振荡器设计方案.     

加性噪声对微波光电振荡器相位噪声的影响

微波光电振荡器是一种基于微波光子技术的高频微波信号发生装置,它能够产生超高频谱纯度及超低相位噪声的微波信号。研究了典型的微波光电振荡器相位噪声产生机理及相位噪声谱密度。从构成微波光电振荡器的核心器件出发,分析了开环状态下,微波光电振荡器中的加性噪声来源及其对相位噪声的影响。     

基于数字锁相的Ku波段频综器研究

针对一种Ku波段频综器阐述了基于数字锁相的跳频环路参数选择及对其相位噪声、杂散、稳定性的影响,研究了Ku波段频综器的设计思想,并对整体相位噪声进行了估计。工程实现结果表明,理论估值与实现结果基本一致。     

低相位噪声微波振荡器设计

针对Ka和Ku波段上、下变频装置对微波振荡器低相位噪声和小型化的要求,该文采用单环锁相式频率合成技术完成了微波振荡器的设计,并对锁相环的相位噪声进行了理论计算。分析了鉴相频率、鉴相器灵敏度和环路带宽对锁相环输出相位噪声的影响,根据分析结果对微波振荡器电路参数合理选择,同时兼顾了低相位噪声与小型化的设计要求。测试结果表明,振荡器的相位噪声指标与理论计算一致,各项指标均达到要求,可满足实际工程应用。     

耦合式光电振荡器的理论与实验研究

为了研究耦合式光电振荡器,阐述了耦合式光电振荡器的模式选择理论,给出了维持最佳锁模状态的相位匹配条件,分析了影响射频信号相位噪声的因素,进行了基于保偏机制的耦合式光电振荡器的实验研究。采用分别调节光环形腔和光电微波振荡环路中的保偏可变光纤延迟线可改变腔长的方法,获得了腔长与振荡频率的关系。同时,采用鉴频法测量了不同条件下5GHz射频信号的相位噪声,研究了影响射频信号相位噪声的因素。结果表明,耦合式光电振荡器的振荡模式取决于光环形腔的腔长,射频信号相位噪声受到光信号偏振态、相位匹配、环路长度等因素的影响。实验中获得了偏移频率10kHz处相位噪声达到-136dBc/Hz的5GHz射频信号,是目前国内已知的相位噪声最低的耦合式光电振荡器。     

光电振荡器北大核心CSCD

依托微波光子学的发展,光电振荡器采用光电反馈环路技术,将激光能量转换为微波信号能量,摆脱了传统微波振荡器随频率升高相噪性能会降低的限制,能以光、电两种形式输出稳定的低噪声信号,成为一种新型的高质量微波信号源。光电振荡器不仅具有一定的可调谐性能,而且能够产生频率从几GHz到上百GHz、Q值高达1010的电信号,具有广阔的应用前景,受到了广泛的关注。文章阐述了光电振荡器的研究现状,对光电振荡器的相位噪声、边模抑制、频率稳定性、频率可调谐性、高频输出、集成化等方面进行简要概括。     

激光器对光电振荡器相位噪声的影响

为了改善光电振荡器相位噪声特性、提高光电振荡器性能,采用理论分析和实验验证的方法,研究了激光器线宽、光功率与光电振荡器相位噪声之间的关系.测试了激光器在功率相等、线宽不等情况下,光电振荡器所产生的微波信号的频谱特性和相位噪声特性;测试了给定线宽激光器在不等功率情况下,所产生的微波信号的相位噪声特性.结果表明,激光器线宽越窄、光功率越大,光电振荡器产生微波信号的频谱特性和相位噪声特性就越好;在频偏1kHz以外,相位噪声受激光器线宽影响较小,受光功率影响较大.这一结果对改善光电振荡器相位噪声有一定的帮助.     

基于ADF4106的恒定环路带宽宽覆盖频合器设计

提出了一种基于鉴相电流可实时调节特性的宽相对覆盖、低相位噪声的捷变频频率合成方法.该方法主要针对频合器在宽频率覆盖时会遇到环路带宽变化剧烈的问题,提出通过实时调节ADF4106的鉴相电流,对压控振荡器的等效压控增益非线性进行补偿,从而实现在宽覆盖范围内锁相环的环路带宽基本保持恒定.基于本方法研制实现了以ADF4106为核心的宽频率覆盖微波频合器;其全范围环路带宽基本恒定在600 kHz,并具有良好的低相噪指标和捷变频性能.由于该方法显然也适用于其它具有程控鉴相电流功能的PLL专用芯片,故对于研制高性能频率合成器具有非常重要的现实意义.     

CMOS毫米波低相噪级联双锁相环频率综合器设计北大核心

采用65 nm CMOS工艺，设计了一种低相噪级联双锁相环毫米波频率综合器。该频率综合器采用两级锁相环级联的结构，减轻了单级毫米波频率综合器带内和带外相位噪声受带宽的影响。时间数字转换器采用游标卡尺型结构，改善了PVT变化下时间数字转换器的量化线性度。数字环路滤波器采用自动环路增益控制技术来自适应调节环路带宽，以提高频率综合器的性能。振荡器采用噪声循环技术，减小了注入到谐振腔的噪声，进而改善了振荡器的相位噪声。后仿真结果表明，在1.2 V电源电压下，该频率综合器可输出的频率范围为22～26 GHz,在输出频率为24 GHz时，相位噪声为-104.8 dBc/Hz@1 MHz,功耗为46.8 mW。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first