可调电子束注入器调配调谐结构的设计及分析（英文）

驻波谐振腔是基于直线加速器的束流注入器的基本构造元件,其大功率微波馈入一般选用矩形波导耦合器,但它会引起场不对称和谐振频率的漂移,也难以针对不同流强的束流灵活调节耦合度。建立了带有调配杆的耦合器的等效电路模型,在理论分析的基础上,给出了杆的最佳位置。此外,在耦合器的对称方向插入调谐杆用于补偿结构改变及加工安装等外部因素造成的频率漂移,并使用CST MICROWAVE STUDIO的三维电磁仿真给出了两个杆的尺寸和调整范围。联合调整的仿真结果表明,在谐振频率保持稳定的情况下,不同流强的束流均达到临界耦合状态,从而避免了耦合器失配引起的反射功率风险,并减少了由于较小耦合孔引起的场不对称。     

750 keV射频四极注入器射频结构的优化

 设计了750 keV,201.25 MHz的RFQ注入器的射频结构,对四杆型RFQ结构进行了简要的理论分析,在束流动力学设计的基础上,对射频结构进行了优化。研究了四杆型RFQ结构中支撑板高度、宽度、厚度、间距、形状、外腔体半径等因素对射频特性的影响,进行了优化设计并给出了主要的结构参数及射频特性的设计结果。优化设计得到的四杆型RFQ腔体长度126 cm,在极间电压80 kV时,峰值功率损耗为115.95 kW,二极场因子为1.004,电场沿轴向分布比较均匀,偏差小于3.5%,满足了物理需求。     

750 keV射频四极注入器水冷设计

750 keV,201.25 MHz的射频四极注入器为四杆型,电极长度124 cm,共16个支撑板。根据加速器射频结构设计的结果进行了水冷管道的结构设计,理论分析了管路的流体力学特性和传热学特性。在忽略结构形变的情况下,利用射频计算软件的稳态热分析功能计算了加速腔的温度分布,降低了模拟计算的难度。计算结果表明:加速腔的最大温升控制在1 K以内,水冷系统能够使加速器在适宜的温度下长时间稳定运行,设计结果很好地满足了物理需求。     

750 keV射频四极注入器束流动力学设计

描述了一台750 keV,201.25 MHz的射频四极注入器束流动力学设计。在考虑与35 MeV质子直线加速器匹配、功耗小、传输效率高等原则的基础上,提出了加速器的技术要求。给出了两套设计方案的主要参数和设计结果。分析了能散度、发射度、Twiss参数、注入流强和能量等参数在非理想匹配条件下对束流传输效率的影响。比较了两套方案的异同点。模拟计算结果表明,两套设计方案均可以满足物理要求,传输效率都在99.3%以上。     

750 keV射频四极注入器束流动力学设计

 描述了一台750 keV,201.25 MHz的射频四极注入器束流动力学设计。在考虑与35 MeV质子直线加速器匹配、功耗小、传输效率高等原则的基础上,提出了加速器的技术要求。给出了两套设计方案的主要参数和设计结果。分析了能散度、发射度、Twiss参数、注入流强和能量等参数在非理想匹配条件下对束流传输效率的影响。比较了两套方案的异同点。模拟计算结果表明,两套设计方案均可以满足物理要求,传输效率都在99.3%以上。     

宽调谐范围垂直腔面发射激光器特性分析及设计

运用光学传输矩阵和有限元方法对波长可调谐垂直腔面发射激光器(VCSELs)的波长调谐范围进行了研究.对中心波长为980nm的可调谐VCSELs的波长调谐特性和微电子机械系统(MEMS)悬臂梁结构进行了设计，并进行了实验研究.结果表明，MEMS可调谐VCSELs调谐特性同时受到光波谐振腔结构和悬臂梁最大位移的共同影响.在悬臂梁几何尺寸和激光器有源区结构一定的条件下，通过优化可调谐VCSELs的牺牲层厚度可实现大范围波长调谐.同时，对可调谐VCSELs整体结构进行了设计，计算结果显示波长调谐范围达到30nm以 关键词： 悬臂梁 可调谐垂直腔面发射激光器     

C-ADS注入器Ⅱ项目RFQ射频系统介绍（英）

C-ADS注入器Ⅱ的RFQ射频系统是该强流加速器的关键一环,它通过两台完全一样的耦合器为一台四边形四翼型RFQ提供和传送功率。该射频系统在设计之初就考虑为10 mA连续束流而进行特殊优化,从功率源、耦合器和功率传输系统几个方面对其进行详细介绍,尤其是针对CW模式下的系统稳定运行以及设备可靠性等方面进行的特殊考虑和模拟方法。该系统已经在2015年通过了10 mA连续束的测试,证实了该射频系统的设计和调试符合物理的实验需求。特别阐述了该系统中一种新的碗型陶瓷窗耦合器的设计思路和一种无环形器情况下的特殊的耦合系数调谐方法,同时推导了双端口耦合的计算方法的具体设置过程。     

C-ADS注入器Ⅱ项目RFQ射频系统介绍（英）

C-ADS注入器Ⅱ的RFQ射频系统是该强流加速器的关键一环,它通过两台完全一样的耦合器为一台四边形四翼型RFQ提供和传送功率。该射频系统在设计之初就考虑为10 mA连续束流而进行特殊优化,从功率源、耦合器和功率传输系统几个方面对其进行详细介绍,尤其是针对CW模式下的系统稳定运行以及设备可靠性等方面进行的特殊考虑和模拟方法。该系统已经在2015年通过了10 mA连续束的测试,证实了该射频系统的设计和调试符合物理的实验需求。特别阐述了该系统中一种新的碗型陶瓷窗耦合器的设计思路和一种无环形器情况下的特殊的耦合系数调谐方法,同时推导了双端口耦合的计算方法的具体设置过程。     

光阴极注入器型能量回收射频加速器

 光阴极注入器型能量回收射频加速器（PERL）是新一代加速器，在高平均功率自由电子激光和下一代高亮度光源等研究中有很好的应用前景。分析了PERL的强流与高平均功率特性，对注入器输出束流品质的要求及光阴极注入器、超导加速腔等关键技术进行了研究，设计分析了一种特殊结构的高压DC Gun光阴极注入器，能有效地提高DC加速腔中的加速场强，当高压为1MV和加速场达到10MV/m时，产生的电子束流能够基本满足PERL应用要求。同一超导加速段中的束流加速和能量回收的数值模拟计算结果表明，能获得高效率电子束流能量回收效果。     

光阴极注入器型能量回收射频加速器

光阴极注入器型能量回收射频加速器（PERL）是新一代加速器,在高平均功率自由电子激光和下一代高亮度光源等研究中有很好的应用前景。分析了PERL的强流与高平均功率特性,对注入器输出束流品质的要求及光阴极注入器、超导加速腔等关键技术进行了研究,设计分析了一种特殊结构的高压DC Gun光阴极注入器,能有效地提高DC加速腔中的加速场强,当高压为1MV和加速场达到10MV/m时,产生的电子束流能够基本满足PERL应用要求。同一超导加速段中的束流加速和能量回收的数值模拟计算结果表明,能获得高效率电子束流能量回收效果。     

Design of a thermal tunable photonic-crystal coupler

Wavelength division multiplexing (WDM) is a common technique used to increase the capacity of optical communication networks. In this technique, data coming from different sources are transmitted through the same optical fiber using different optical carriers. We study a thermally controlled tunable photonic-crystal optical coupler. The device is designed using a triangular lattice of air holes in an epitaxially layered structure (InGaAsP/InP). In this configuration, the input and output waveguides are separated from each other, in contrast to other devices that require a reflective grating and circulators or beam splitters. We use the two-dimensional finite-difference time-domain method (2D-FDTD) to analyze the performance of this device. After optimization the parameters of this device, we study the effects of changing the temperature. Not only has the position of the resonant peak changed linearly with the temperature, but the efficiency is also doubled. A linear regression of the spectral response gives a slope of dλ/dT = +0.1 nm/°C in a temperature range of ΔT = 50°C for wavelengths close to 1550 nm. These results show the possibility of tuning this contra-directional coupler using the thermo-optical effect.     

Design and analysis of thermally tunable liquid crystal filled hybrid photonic crystal fiber coupler

We propose a novel tunable photonic crystal fiber (PCF) coupler scheme, that the light is coupled between a total internal reflection (TIR) guiding core and a photonic bandgap (PBG) guiding core. By introducing the thermo-optic responsive nematic liquid crystals (NLC) into the air holes around the PBG core, the hybrid PCF based coupler exhibits enhanced thermal tunability. The thermo-optical characteristics of the proposed coupler are numerically studied using finite element method (FEM) and beam propagation method (BPM). The proposed design can find promising applications in filtering and sensing devices.     

Fast tunable coupler for superconducting qubits

A major challenge in the field of quantum computing is the construction of scalable qubit coupling architectures. Here, we demonstrate a novel tunable coupling circuit that allows superconducting qubits to be coupled over long distances. We show that the interqubit coupling strength can be arbitrarily tuned over nanosecond time scales within a sequence that mimics actual use in an algorithm. The coupler has a measured on/off ratio of 1000. The design is self-contained and physically separate from the qubits, allowing the coupler to be used as a module to connect a variety of elements such as qubits, resonators, amplifiers, and readout circuitry over distances much larger than nearest-neighbor. Such design flexibility is likely to be useful for a scalable quantum computer.     

一种硅基SiO2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。     

一种波束赋形可调的导航天线设计

提供一种新的调节半功率波束宽度的思路,并设计了一款可实现波束宽度变换以应用于不同波束赋形场景的北斗二号B3频段的导航天线。基于四阵元双馈源的微带贴片天线阵列,在HFSS有限元仿真软件中根据理论进行建模仿真并优化。在保持右旋圆极化的基础上,不用改变阵列的结构,只需适当调节各个阵元激励的幅度与相位,就能实时缩小或者扩大半功率波束宽度,分别实现主瓣方向可调的定向波束赋形与宽波束赋形以应对不同的工作环境,并且具有定向抗干扰能力。仿真结果表明:定向波束赋形与宽波束赋形在B3中心频点的最大增益分别约为7.13,3.56 dBi,半功率波束宽度分别为52°,119°,3 dB轴比宽度分别为90°,166°;在整个B3频段内各个馈电端口反射系数低于?11 dB,相邻端口隔离度低于?28 dB。设计的波束赋形方式可调的导航天线适用于在无遮挡的开阔空间与特定的遮挡环境之间经常切换的工作场景,改善传统的机动式导航终端在“城市峡谷”等高遮蔽角环境下增益较低的缺点。     

Design and characterization of a tunable DNG metamaterial superstrate for small beam steering antennas

The design and the characterization of a tunable double negative metamaterial is proposed in order to create a superstrate for beam steering applications in small antennas. The tunable metamaterial is based on an omega shaped unit cell and is investigated and validated by waveguide measurements. An appropriate loading of the metamaterial unit cell, through the use of a varactor diode, enables to vary the medium index of the superstrate within an interesting range. This metamaterial superstrate is then associated to a patch antenna in its near field zone permitting to steer the beam in several directions within elevation plane.     

一种新型可调谐红外滤光片的设计和应用

可调谐红外滤光片是高分辨率红外成像仪谱段识别和分光的重要光学器件.本文介绍了一种新型可调红外滤光片———液晶法布里-珀罗滤光片的基本原理、设计参数、制作方法,分析了这种滤光片的透射光谱、精细度、带宽、镜面反射率和腔长之间的关系,以及外加电压和温度对透射波长的影响,给出了消除偏振效应的几种方案.并对液晶法布里-珀罗滤光片在空间遥感,特别是红外探测方面的应用前景进行了展望.     

Design and analysis of a noncollinear acousto-optic tunable filter

The design of the noncollinear acousto-optic tunable filter (AOTF) is commonly based on the parallel tangents momentum-matching condition. Previous studies either have used an approximation of the birefringence of the interaction material or have ignored the rotatory property of TeO(2). These approaches would obviously decrease the accuracy of designing an acousto-optic tunable filter (AOTF). We introduce an analysis method of calculating the optimum incident optical angle. Besides, an appropriate optical wedge on the output optical facet is designed to reduce the wavelength dependence of the diffracted beam angle, which is very significant in practical applications of AOTF.     

Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

In this paper a compact polarization beam splitter based on a deformed photonic crystal directional coupler is designed and simulated. The transverse-electric （TE） guided mode and transverse-magnetic （TM） guided mode are split due to different guiding mechanisms. The effect of the shape deformation of the air holes on the coupler is studied. It discovered that the coupling strength of the coupled waveguldes is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.Sttm. A finite-difference tlme-domain simulation is performed to evaluate the performance of the device, and the extinction ratios for both TE and TM polarized light are higher than 20 dB.     

Design and analysis of a novel tunable optical power splitter

A novel tunable optical power splitter,with a Y-branch waveguide based on the total internal reflection and a microprism with tunable index refraction,is presented.Numerical simulation of its optical performance shows that a high dynamic range,low optical loss,and relatively low wavelength-dependence can be achieved.This component offers numerous advantages such as ease for fabrication,low cost,and compact size,which are very useful for potential application in integrated optical devices.