波导调制器的光束传播法设计

以光束传播法分析马赫－陈德尔型波导电光强度调制器的波导宽度，Ｙ型分支角、调制电压等参量与器件特性之间的关系，有利于Ｍ－Ｚ波导电光调制器的优化设计。     

Upgrade of beamline BL08B at Taiwan Light Source from a photon‐BPM to a double‐grating SGM beamline

During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam‐position monitor (BPM) to a testing beamline and a single‐grating beamline that enables experiments to record X‐ray photo‐emission spectra (XPS) and X‐ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X‐ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano‐fabrication and topological thin films are increasing. The basic spherical‐grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420 eV. Four end‐stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme‐ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in the L‐edge adsorption spectrum.     

X-Ray Crystallography and Free Energy Calculations Reveal the Binding Mechanism of A2A Adenosine Receptor Antagonists

We present a robust protocol based on iterations of free energy perturbation (FEP) calculations, chemical synthesis, biophysical mapping and X-ray crystallography to reveal the binding mode of an antagonist series to the A_2A adenosine receptor (AR). Eight A_2AAR binding site mutations from biophysical mapping experiments were initially analyzed with sidechain FEP simulations, performed on alternate binding modes. The results distinctively supported one binding mode, which was subsequently used to design new chromone derivatives. Their affinities for the A_2AAR were experimentally determined and investigated through a cycle of ligand-FEP calculations, validating the binding orientation of the different chemical substituents proposed. Subsequent X-ray crystallography of the A_2AAR with a low and a high affinity chromone derivative confirmed the predicted binding orientation. The new molecules and structures here reported were driven by free energy calculations, and provide new insights on antagonist binding to the A_2AAR, an emerging target in immuno-oncology.     

一种硅基SiO_2波导耦合器的设计与分析

波导耦合器是组成光纤传感系统和光纤通信系统光收发组件及模块的重要元器件,是实现光收发模块一体化光电集成的基础。给出了一种用光纤陀螺系统的X型四端口波导耦合器的工作原理,采用有效折射率法和BPM(Beam propagation method)法建立了耦合器的数学模型,计算并分析了耦合器尺寸在尽可能小的情况下和在满足单模传输的条件下耦合器的耦合系数、有效耦合长度、分光比以及回波损耗等参数之间的关系,并对其关键技术进行了系统的研究。仿真结果表明,所设计的波导耦合器在低损耗情况下分光比可达到50%∶50%,耦合器全长为33.5mm,输入输出波导间距为410μm,芯层截面积为6μm×6μm。     

Study on inverse taper based mode transformer for low loss coupling between silicon wire waveguide and lensed fiber

We have simulated the coupling loss of three types of Inverse Taper and taper-lensed fiber using three dimensional (3D) semi-vectorial beam propagation methods (BPM) respectively. Our results showed that the performances of exponential inverse taper and quadratic inverse taper were better than the commonly used linear inverse taper. Especially, for TM mode the improvement in the reduction of devices size is 53% and 136% for exponential and quadratic inverse taper compared with the linear inverse taper.     

快速计算阵列波导光栅波导耦合系数的修正重叠积分方法

提出了一种修正的重叠积分方法用以计算阵列波导光栅(AWG)波分复用器件中光从自由传输区域到阵列波导的耦合系数,并和光束传播法(BPM)数值方法计算得到的结果做了比较通过比较分析,得出结论:当波导中心距不是太小时,用修正重叠积分这一快速方法是合适的.     

弯曲波导之间的耦合分析

采用极坐标下的光束传播法分析了两条平行变曲波导的中心间距、曲率半径等因素对模式耦合的影响,得到了耦合长度、耦合强度随中心间距、曲率半径的变化规律,并将直波导作为变曲波导的一种特殊情况进行了分析.     

束流位置监测系统的研制及其在国家同步辐射实验室二期工程中的应用

 介绍一种储存环束流位置监测系统的标定装置。这套标定装置是为NSRL二期工程储存环注入段真空盒改造而研制的。系统的标定精度达±0.01mm。该装置已用于新增注入段真空管的束流位置探测器的定标，获得了探头定标值，并根据其拟合和计算结果对注入段真空管进行了筛选，被选中的真空管已装入储存环注入段。     

Calculation of the spectral response of an arrayed-waveguide gating demultiplexer with a wide-angle beam propagation method in a cylindrical coordinate system

The spectral response of an arrayed-waveguide grating (AWG) demultiplexer is calculated by simulating the field propagation in the output section of an AWG with a wide-angle beam propagation method (BPM) in a cylindrical coordinate system. As in a practical design of an AWG demultiplexer, each output waveguide consists of two straight sections connected by a bending section. The spectral response obtained by the present algorithm is more accurate than those obtained with two popular approximate methods, namely, the conventional overlapped integral method and the standard BPM for radially straight and infinitely long output waveguides. With the present algorithm, the dependence of the spectral response on the parameters of the output section is analyzed. The channel crosstalk and the 3 dB passband width of the spectral response depend mainly on the length of the first straight section, the end separation and the angular separation of the output waveguides. The bending section results in an asymmetrical spectral response with remarkable sidelobes which can be reduced by increasing the bending radius.