1064nm低电压薄膜铌酸锂电光调制器

低半波电压电光调制器是实现大规模光电集成的关键。文章提出了一种半波电压低于1.5 V的薄膜铌酸锂马赫-曾德尔(Mach-Zehnder, MZ)电光调制器，选用绝缘体上单晶薄膜铌酸锂材料作为设计基础，分析了直波导、多模干涉耦合器、弯曲波导和调制臂等结构对电光调制器的影响。结果表明，当调制臂长为3 mm时，该薄膜铌酸锂电光调制器具有1.05 V的低半波电压、0.319 dB的低损耗和27 dB的高消光比。同时，该调制器半波电压长度积为0.315 V·cm,调制效率高，具有与CMOS技术兼容的半波电压，有利于大规模光电集成。     

全封装的薄膜铌酸锂电光调制器（特邀）

高速电光调制器是宽带光通信网络和微波光子系统中的关键元器件之一。相对于体材料铌酸锂而言,薄膜铌酸锂材料由于其较强的光场限制能力,在构建小尺寸、宽带、低半波电压的高性能电光调制芯片上有独特的优势。文章基于薄膜铌酸锂材料研制了一种3 dB带宽不低于50 GHz的电光调制芯片,并采用光纤与波导水平端面耦合的光学封装方案和基于1.85 mm同轴接头的射频封装方案,实现了全封装的薄膜铌酸锂电光调制器。测量结果表明,封装后器件的光学插入损耗小于等于5 dB,3 dB带宽大于等于40 GHz,射频半波电压小于等于3 V@1 GHz。     

高性能硅和铌酸锂异质集成薄膜电光调制器 （特邀）

硅基光子集成平台因其高集成度、CMOS工艺兼容性等特点在光通信领域受到了广泛的关注,而电光调制器作为光通信系统中最为重要的器件之一,承担着将电信号加载至光信号上的关键作用,为打破硅基调制器的性能限制,可利用硅和铌酸锂的大面积键合技术以及铌酸锂低损耗波导刻蚀技术实现高性能硅和铌酸锂异质集成薄膜电光调制器,目前该类调制器的性能可达半波电压3 V,3 dB电光带宽超过70 GHz,插入损耗小于1.8 dB, 消光比大于40 dB。文中对比了硅和铌酸锂异质集成调制器的研究现状并介绍了该异质集成薄膜调制器的结构设计与工艺实现方法。     

高速铌酸锂电光调制器研究进展

薄膜铌酸锂调制器因其小尺寸、高带宽、低半波电压等优点,成为近年来业内关注的热点。文章梳理了铌酸锂电光调制器的波导结构、电极结构及偏置点控制技术三个方面的相关研究进展,分析了平面掩埋、脊型、光子晶体等三种不同结构波导的调制器性能,讨论了铌酸锂调制器集总和行波两种电极结构的特点及其设计考量因素,对比了电光调制器偏置点控制中功率法和导频法的优缺点及其相关研究成果。在此基础上,进一步分析了为实现更小体积与更高带宽铌酸锂调制器所需的关键技术以及未来的研究方向。     

一种基于薄膜铌酸锂调制器芯片的新型电光调制器

针对传统铌酸锂电光调制器体积大、带宽小等技术问题,提出了一种基于薄膜铌酸锂调制器芯片的新型电光调制器的设计方法,给出了薄膜铌酸锂电光调制器高频传输仿真模型,详细介绍了薄膜铌酸锂电光调制器的高频信号馈入设计、过渡薄膜基板高频阻抗匹配设计,并测试了40 GHz小尺寸薄膜铌酸锂电光调制器的核心指标。测试结果表明：设计的薄膜铌酸锂电光调制器插入损耗、半波电压、3 d B带宽、产品尺寸分别为4.1 d B、3.9 V、40 GHz、30 mm×10 mm×5 mm,比传统铌酸锂电光调制器性能优越。     

铌酸锂低半波电压电光调制器研究

对降低铌酸锂(LN)电光调制器的半波电压进行了研究,探索了利用反射结构实现低半波电压的原理.通过退火质子交换工艺在x切LN晶片上制作了反射结构的LN电光调制器.测试表明,这种反射结构的LN电光调制器在保持器件长度不变的条件下可以降低半波电压.     

集成光学光纤陀螺芯片

本文首次报道了国内研制的集成光学光纤陀螺芯片,详细描述了其设计考虑与制作。单 Y 型多功能钛扩散铌酸锂芯片包含消光比大于35dB 的薄膜波导偏振器、分束比为49.5/50.5的3dB 分束器/合束器、半波电压小于5伏的相位调制器,光纤—器件—光纤插入损耗为5.4dB。     

交叉耦合效应对M-Z调制器谐波抑制比的影响

针对微波光子链路低噪声高线性度的应用需求,研究了Mach-Zehnder (M-Z)型电光调制器波导交叉耦合效应对谐波抑制比的影响。首先通过OptiBPM和MATLAB联合仿真发现波导间交叉耦合效应会导致调制器射频电极与偏置电极工作点的偏移,进而降低谐波抑制比;其次利用特制的窄波导间距铌酸锂调制器实测验证了该现象,最后提出了一种能快速检测M-Z型电光调制器交叉耦合效应的方法。文章不仅探索了波导结构对谐波抑制比的影响,还为用于微波光子技术的脊波导及光子晶体薄膜铌酸锂调制器的研制提供了一定参考。     

基于激光相控阵原理的相位调制器半波电压测量方法

半波电压是电光相位调制器的一个重要指标, 针对现有半波电压测量方法存在的测量误差大、测量装置复杂等问题, 提出了基于激光相控阵光束扫描原理的半波电压测量方法.通过理论分析, 得到了远场主光束的偏移量和相位调制器半波电压的关系表达式.搭建了12 全光纤激光相控阵光路, 对铌酸锂波导相位调制器的半波电压进行了实验测量, 改变相位调制器的加载电压, 记录多幅远场光强分布图, 通过求平均值减小测量误差, 而且根据远场光强分布的变化得到了相位调制特性曲线.结果表明, 该方法测量装置简单, 不仅可以精确地测量半波电压, 还可以对相位调制线性度进行分析, 具有重要的工程应用价值.     

LiNbO3电光调制器的优化设计与制作

铌酸锂晶体有良好的光声和电光性质,因而基于铌酸锂的集成光学器件已引起人们广泛关注。利用LiNbO3作为介质材料,设计M-Z干涉型强度调制器。选用低损耗的质子交换光工艺技术制备光波导。对质子交换铌酸锂光波导的制作工艺、波导特性及其应用进行了研究。对电极结构进行了优化设计。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.