环形激光器反射镜相位延迟差测量方法研究

理论上推导出了环形激光器对Ｓ光和Ｐ光相位延迟差与其拍频峰对应的压电陶瓷电压差的关系式,分析了方形环形激光器对Ｓ光和Ｐ 光的频率响应特性,通过测量拍频峰电压差实现环形激光器反射镜相位延迟差测量。通过搭建环形激光器频率响应特性测试系统,从实验上验证了理论计算的正确性。结果表明,该方法测量误差小于１．５％,满足环形激光器反射镜相位延迟差测量要求。     

极性反转结构电光波导调制器的频域响应分析

本文详细分析了具有极性反转电极结构电光调制器的响应特性，推导出器件输出端振幅和相位的频率响应的解析表达式，并给出相应的数值计算结果．     

极性反应结构电光波导调制器的频域响应分析

本文详细分析了具有极性反转电极结构电光调制器的响应特性，推导出器件输出端振幅和相位的频率响应的解析表达式，并给出相应的数值计算结果。     

基于双音外差的电光相位调制器半波电压自校准测量方法

电光相位调制器是光纤通信系统、微波光子系统和相干光通信系统中的关键器件之一. 作为器件本征参数, 电光相位调制器的半波电压通常利用光谱方法和电谱方法进行测量. 光谱方法受到光源线宽和光谱仪分辨率限制, 测量的分辨率较低; 电谱方法则需要光电检测之前将相位调制转换成强度调制, 电谱方法的主要困难在于需要对探测器的不平坦响应进行额外校准. 提出了利用双音外差实现电光相位调制器半波电压自校准测量新方法, 该方法利用双音电光相位调制的边带与移频光载波的外差拍频, 对外差拍频信号进行频谱分析, 获得电光相位调制器的半波电压; 通过设定双音调制信号的频率关系, 克服了探测器光电转换中的不平坦频率响应, 实现了自校准测量. 该方法可扩展探测器和频谱仪的测试频率两倍以上, 节省至少一半的带宽需求. 与光谱测量方法相比, 该方法测试分辨率大幅提高且避免了光源线宽的影响; 与传统电域测量方法相比, 该方法无须额外校准, 无驱动功率和工作波长限制, 且对测试仪器带宽需求降低一半以上. 实验证实了所提方法获得的电光相位调制器半波电压的测量结果与光谱分析法获得的结果一致, 且大幅度地提高了测量范围和分辨率. 该方法提供了非常简单的电光相位调制器微波特性化分析方法, 对其他光电子器件分析也提供了参考.     

80 Gb/s高速PAM4调制850 nm垂直腔面发射激光器

展示了高速直接调制850 nm氧化物限制垂直腔面发射激光器（VCSEL）的结果。优化设计应变InGaAs/AlGaAs量子阱以实现高微分增益,通过表面刻蚀来调节光子寿命实现响应平坦化。研制的氧化物孔径约7μm的VCSEL具有平坦的频率响应,3 dB调制带宽为24 GHz,相对噪声强度值-155 dB/Hz,未采用任何预加重和均衡技术情况下PAM4调制数据传输速率达80 Gb/s。     

阶梯分段准相位匹配结构的平坦宽带波长转换

利用龙格-库塔法分析了阶梯分段准相位匹配结构对基于差频效应的波长转换器的转换带宽、转换效率及平坦性的影响.当晶体长度不变时,增加阶梯段数,设计合理的起始段极化周期及合理的阶梯变化量,可以同时获得高平坦性、大转换带宽和高转换效率的波长转换.分析了结构参数对波长转换特性的影响.对于3cm长的晶体,在保证平坦度低于0.2dB的前提下,得到166nm的转换带宽和-0.55dB的最大转换效率.对比分析了阶梯分段结构的波长转换器与正弦啁啾光学超晶格和分段光栅结构的波长转换器的特性,结果表明阶梯分段结构与正弦啁啾光学超晶格相比在转换效率、带宽和平坦度方面都占优势;与分段光栅结构相比,转换带宽稍小,但转换效率和平坦度都更大.     

增益平坦拉曼放大器优化算法研究

在分析受激拉曼散射耦合方程的基础上，介绍了一种反向设计多波长抽运光纤拉曼放大器的方法，并使用一种改进遗传算法和新型打靶法，讨论了体现特定的高增益和宽带平坦的适应度函数，对抽运波长和功率进行了优化，得到高增益，宽带平坦的增益谱，其开关增益可达15dB，增益带宽达80nm，增益波动小于1dB，这种放大器结构比现有的宽带光纤放大器在增益平坦上有一定的进步。     

行波电极硅-有机复合集成电光调制器理论分析与实验研究

对基于行波电极的硅-有机复合集成电光调制器进行研究,构建调制器的波导电极结构模型,分析特征阻抗和微波有效折射率对调制器频率响应的影响。通过对电极结构的仿真优化,完成调制器芯片的设计与制备,研究电光聚合物材料的片上极化工艺,得到高性能硅-有机复合集成电光调制器。对研制调制器电极的电学S(Scatter)参数进行测试,分析得到的电极特征阻抗和有效折射率与仿真设计结果基本相符。测试得到电光调制器的3 dB带宽大于50 GHz。     

硅微ZnO压电薄膜传声器的研制

本文介绍了一种利用ZnO压电薄膜为换能器的硅微压电薄膜传声器的制备,并且对微机械加工工艺过程进行了较为详细的描述。本文对传声器的部分结构进行改进,与通常设计相比较大幅提高了传声器的性能,1000Hz基准频率的灵敏度达到-85dB(相对于1V/Pa),500Hz到10000Hz的频率响应的平坦度在±3dB范围内。     

固体FTIR光声光谱的共振增强

我们在FTIR光声光谱测量工作中首次观察到由光声池频率响应特性造成的光声信号共振增强现象.研究表明,这种效应起源于样品腔中气体传声器对声压信号的响应不平坦.文中讨论了利用此效应提高光声检测灵敏度和信噪比的可能性,并且给出了一个利用共振增强方法研究导电聚合物PTh样品中SP_3结构缺陷的实例.     

Electrochemical properties of thin TiO2 electrode on Li1 + xAlxGe2 − x(PO4)3 solid electrolyte

A fabrication of all-solid-state thin-film rechargeable lithium ion batteries by sol-gel method is expected to achieve both the simplification and cost reduction for fabrication process. TiO₂ thin film electrode was prepared by PVP (polyvinylpyrrolidone) sol-gel method combined with spin-coating on Li_1 + xAl_xGe_2 − x(PO₄)₃ (LAGP) solid electrolyte which has wide electrochemical window. The thin film was composed of anatase TiO₂ that is the most active phase for Li insertion and extraction and contacted well with LAGP substrate. In the cyclic voltammogram, a redox couple was observed at 1.8 V vs. Li/Li⁺ assigned to Li insertion/extraction into/from anatase TiO₂, indicating that the thin film worked as electrode for lithium battery. The charge and discharge test in various charge and discharge rates revealed that the discharge process (delithiation) is thought to be faster than charge process (lithiation). It is attested that the sol-gel process, which derives both simplification and cost reduction for fabrication process, can be applied to thin film battery using LAGP solid electrolyte.     

Capacitance dispersion in electrochemical impedance spectroscopy measurements of iodide adsorption on Au(1 1 1)

Electrochemical interfaces that display dispersive characteristics do not present the purely capacitive behaviour predicted by the theory of ideally polarised interfaces. For interfaces involving solid electrodes, capacitance dispersion phenomena in the double layer region are usually attributed to the structural characteristics of the electrode surface as well as to the interfacial region. This paper presents a study of the dispersive characteristics, in the double layer potential region, related to the iodide adsorption on an Au(1 1 1) electrode. The study was performed by using electrochemical impedance spectroscopy, and the corresponding spectra fitted with an equivalent circuit containing a constant phase element (CPE). The fitting results are compared with capacitance curves obtained by chronocoulometry, in order to analyse the relationship between the CPE and the interfacial capacitance. It was observed the occurrence of dispersive behaviour in the potential regions associated with phase transition processes in the adsorbed layer and to the potential induced reconstruction phenomena. On the other hand, in the potential regions where such phenomena do not occur, the interface presents almost pure capacitive behaviour. These observations provide evidence of the strong contribution of the solution properties to the capacitance dispersion.     

In situ observation of a Au (1 1 1) electrode surface using the X-ray reciprocal-lattice space imaging method

A rapid X-ray diffraction method was proposed for in situ observation of a surface-intermediate structure on a liquid-solid interface. It used a combination of higher-energy monochromatic synchrotron X-rays in grazing incidence and an X-ray two-dimensional detector. Overall patterns were in situ taken, with one-time exposure, of the reciprocal-lattice space of a Au (1 1 1) electrode surface which was fixed at an angular position. We deduced change in crystal domain shapes of surface intermediates as well as its smaller lattice distortion by observing images of reconstructed surface rods during a surface-structural phase transition from the reconstructed surface to the bulk terminated surface. An anisotropic shape of surface-crystal domains was also observed.     

Fluorescent Si nanoparticle-based electrode for sensing biomedical substances

We have been studying the miniaturization of silicon crystals and the transition from the solid state to the atomistic state. We demonstrated the existence of “sweet spots” in cluster size in the range 1-3 nm that have enhanced chemical, structural, and photo stability. The particles are produced by an electrochemical etching process as dispersion in liquid, and they are reconstituted in films, patterns, alloys, or spread on chips to produce super chips. Unlike bulk, these Si nanoparticle configurations have a spectacular ability to glow in distinct RGB colors. In this paper we describe an electrode sensor built by decorating metal or heavily doped silicon electrode with nanoparticles. We demonstrated amperometric response of the electrode to glucose and compared the response to that of heavily doped silicon wafer decorated with GOx. The all silicon electrode shows improved sensitivity, selectivity and stability. Light induced modulation of the response allows phase sensitive detection. The device is suitable for miniaturization, which may enable in vivo use.     

基于相变原理模拟红色顶发射有机电致发光器件的出光性能

研究了有机发光器件(organic light emitting diodes, 简记为OLED)半透明电极上形成的反射相移对OLED光谱产生调制现象.以红色微腔结构顶发射OLED(top emitting OLED,TOLED)为例,基于微腔理论和传输矩阵理论建立物理模型,采用计算机数值模拟方法,得出结果表明器件发光光谱的调制作用不只局限于有机层厚度,也和反射相移有关.通过改变覆盖到顶电极表面的有机层厚度的简单方法,可以实现对顶电极反射相移的调节,从而改变TOLED光学性能.这一结果为进一步改善器件的性 关键词： 反射相移模拟 红色微腔 顶发射有机发光     

Fabrication of the slanted electrode matrix on tilting 4.5° (1 1 1) silicon

The slanted low electrode matrix is designed and fabricated on one tilting 4.5° (1 1 1) silicon wafer to reduce the actuating voltage of 8×8 micro-electromechanical systems (MEMS) optical switch matrix. Due to compact size of the upper electrode chip and (1 1 1) silicon anisotropic etching in KOH solution, photomask is designed which is to fabricate the slanted low electrode matrix that can be matched with the upper electrode chip and every slanted low electrode has enough space for actuating cantilever. The experimental results show that all of the applied voltages for the full range of actuating micromirrors of 8×8 MEMS optical switch matrix are in the range of 67.2±0.5 V. It is demonstrated that the fabricated slanted low electrode matrix has good consistency and every slanted low electrode can be precisely aligned with one-to-one corresponding upper electrodes.     

Measurement of the surface charge density of CO-saturated Pt(1 1 1) electrodes as a function of potential: the potential of zero charge of Pt(1 1 1)

From measurements of the charge flowing upon immersion, at controlled potential, of a CO-covered Pt(1 1 1) electrode in a 0.1 M HClO₄ solution, the corresponding surface charge density vs. potential curve was obtained, and from this the potential of zero charge (pzc) of the CO-covered Pt(1 1 1) electrode. From these data it was estimated that the error incurred when the potential of zero total charge (pztc) of Pt(1 1 1) electrodes is determined by the CO-charge displacement method is of approximately 50 mV at pH 1 and of approximately 90 mV at pH 3. Furthermore, the experimentally determined pzc of the CO-covered Pt(1 1 1) electrode has allowed us to make an estimation of the potential of zero free charge (pzfc) of Pt(1 1 1) electrodes.     

Boron and indium substitution in GaAs(0 0 1) surfaces: Density-functional supercell calculations of the surface stability

Using the density-functional method and surface supercells the surface formation energies are calculated for the most stable GaAs(0 0 1) surface reconstructions without and with up to four indium or/and boron substitutions. Optimal conditions for the growth of the alloys are derived from calculated surface stability diagrams. The incorporation of indium into GaAs without phase separation is possible under strong As-rich conditions and medium to In-rich conditions. Less As-rich conditions can lead to the formation of an InAs phase. Ga-rich conditions give an InGa phase. Isovalent boron incorporation into GaAs without phase separation is possible under strong arsenic and reduced boron exposure. A BAs phase can be formed under more B-rich conditions. More Ga-rich conditions lead to the boron substitution in arsenic positions. The formed boron dimers can be a starting point for the formation of a boron phase. A true antisite boron substitution is less probable. Using the suitable growth conditions obtained for the ternary alloys it is energetically more favourable to incorporate both indium and boron (formation of BInGaAs) than to incorporate only one of the two elements (In or B). The antisite boron incorporation is not favoured in combination with isovalent boron or indium.     

Dynamical response of quantum spin-glass models at t = 0

We study the behavior of two archetypal quantum spin glasses at T = 0 by exact diagonalization techniques: the random Ising model in a transverse field and the random Heisenberg model. The behavior of the dynamical spin response is obtained in the spin-glass ordered phase. In both models it is gapless and has the general form chi(")(omega) = qdelta(omega)+chi(")(reg)(omega), with chi(")(reg)(omega) approximately omega for the Ising and chi(")(reg)(omega) approximately const for the Heisenberg, at low frequencies. The method provides new insight to the physical nature of the low-lying excitations.