用于光探测和测量的环形振荡传感器

在集成电路中,时钟产生器和系统校准广泛采用环形振荡器。通过制造环形振荡器并测量它们的振荡频率,可以获取有关反相电路的传播延迟时间的直接信息。     

基于光电振荡器的低相噪光生微波技术及其应用北大核心CSCD

光电振荡器通过自振荡产生超低相位噪声微波信号,具有光、电两种输出,有望从源头突破现有雷达、电子战等射频系统性能瓶颈。文章介绍了光电振荡器的基本结构和理论模型,回顾了光电振荡器相位噪声、边模抑制比、工作频率、稳定度和小型化等关键性能提升的研究进展,并讨论了光电振荡器的功能拓展及光电振荡器在雷达等领域的应用。     

全国第十二届红外加热暨红外医学发展研讨会在南京召开

据科学时报2009年10月23日报道,2009年10月20日,全国光电测量标准化技术委员会（TC487）在京成立,TC487主要负责光电测量系统名词术语、通用技术、应用技术、光电器件、光电材料特性、光电系统性能参数的校准与测量方法等领域的国家标准制修订工作。     

窄脉冲半导体激光器峰值功率测试及校准方法研究

提出了一种基于波形分析原理实现窄脉冲半导体激光器峰值功率测量的方法,并研究了测试系统的校准技术.此测试系统主要由数字存储示波器和光电转换装簧组成.可直接测量峰值功率.为-r保征测量准确度.根据测量电压与激光脉冲功率的比例关系,溯源争标准激光功率或能量来校准此系统.实验以波长900nm,脉宽为200us和200m的宽、窄两种脉冲半导体激光器为例,采用不同的校准方法分别对测试系统的比例系数k进行标定,并分析了测量不确定度.     

微波超低相噪光电振荡器

介绍了一种基于光纤收发系统的新型微波振荡器.这种光电振荡器由两个反馈光纤延时环组成,各环路中包括光纤、光电探测器、放大器、滤波器和功分器/合成器.光电振荡器具有超低相噪、频谱纯、工作频率高和稳定度高的特点,可广泛应用于微波系统和光纤通信系统.     

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.     

多光谱多光轴设备光轴平行性测量装置研制

多光谱多光轴设备光轴平行性校准装置用于多传感器小型光电测量设备中各探测单元探测光轴平行性的标定和测量,同时具有提供无穷远目标的功能。本文所研制的多光谱多光轴设备校准装置采用卡塞格林反射式平行光管结构,有效通光口径φ350mm,可对可见光系统、中波红外系统、长波红外系统及激光测距系统进行光轴平行性的测量,测量精度优于5″。     

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。     

微波振荡器调制噪声的测量

本文介绍一种测量微波振荡器调制噪声的新方法。测试系统的主要部分是一个运用四端口波导接头的延迟线鉴频器;系统本身为宽频带的,可迅速配备与校准,易于操作并能完全自动化。     

降低光电振荡器相位噪声的方法研究

随着光电振荡器(OEO)技术的飞速发展,改善光电振荡器的相位噪声成为了一个新的研究和发展方向。文章在对光电振荡器的工作原理和特性进行阐述和分析的基础上,对降低光电振荡器相位噪声的技术手段和方案进行了总结,分析了各种方案的基本原理及性能指标。讨论了制约光电振荡器进一步降低相位噪声的因素,提出了可能的发展方向和改进措施。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its