An Optical Path Length Modulator for Laser Diode Self-Mixing Interference

Transparent liquid flattening or stretching realizes optical path length modulation. A flat thin seal transparent cavity, one flank is an electromagnetic driving membrane and is filled over with transparent liquid. Vibration of the membrane makes the liquid compressing or stretching, changes the liquid layer thickness, i.e. the optical path length of light through the liquid layer. The liquid layer compressed is equivalent to increase membrane tension. The membrane has higher resonant frequency. The cavity diameter 10 mm modulation frequency is about 18 kHz.

Improved Superconducting Qubit State Readout by Path Interference

High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequency shift of a microwave cavity from either transmission or reflection. We demonstrate the use of constructive interference between the transmitted and reflected signal to optimize the qubit state readout, with which we find a better resolved state discrimination and an improved qubit readout fidelity. As a simple and convenient approach, our scheme can be combined with other qubit readout methods based on the discrimination of cavity photon states to further improve the qubit state readout.

Second-order interference of two independent and tunable single-mode continuous-wave lasers

The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by em- ploying two-photon interference in Feynman＇s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra.

Second-order interference of two independent photons with different spectra

The second-order interference of two independent photons with different spectra in a Shih-Alley/Hong-Ou-Mandel interferometer is studied in Feynman's path integral theory. There is a second-order interference pattern for photons with different spectra if the photons are indistinguishable for the employed detection system. The conditions to observe the second-order temporal beating with photons of different spectra are analyzed. The influence of the response time of the detection system on the observed second-order interference pattern is also discussed. It is a direct result of that measurement in quantum mechanics is dependent on the employed measuring apparatus. The results are helpful to understand the physics of two-photon interference in different schemes.

Second-order temporal interference of two independent light beams at an asymmetrical beam splitter

The second-order temporal interference of classical and nonclassical light at an asymmetrical beam splitter is discussed based on two-photon interference in Feynman＇s path integral theory. The visibility of the second-order interference pattern is determined by the properties of the superposed light beams, the ratio between the intensities of these two light beams, and the reflectivity of the asymmetrical beam splitter. Some requirements about the asymmetrical beam splitter have to be satisfied in order to ensure that the visibility of the second-order interference pattern of nonclassical light beams exceeds the classical limit. The visibility of the second-order interference pattern of photons emitted by two independent single-photon sources is independent of the ratio between the intensities. These conclusions are important for the researches and applications in quantum optics and quantum information when an asymmetrical beam splitter is employed.

Quantum Path Predictability for an Electronic Mach-Zehnder Interferometer in Presence of Environment Induced Decoherence and Quantum Erasing Process

In this paper, we have estimated the temperature dependent path predictability for an electronic Mach-Zehnder interferometer. The increment of path predictability can directly be associated with stronger decoherence process. We have also theoretically predicted that placing two detectors in both the paths, which are at the same equilibrium temperature with the system, erases all the memory of path information and hence acts like a quantum eraser.

基于双折射晶体透镜的自干涉全息成像系统

该文介绍了采用α–BBO双折射晶体透镜进行分光和光程差补偿方法,以及使用偏振相机进行单次采集的自干涉全息成像方法。该方法不需要使用额外器件补偿共轴干涉光路的光程差,适用于非相干白光照明情况下日常物体的全息图采集与图像重建。该文推导了再现距离与放大率等重要参数,并在此基础上,搭建了单发成像系统,还进行了实验验证。实验通过单次曝光采集了LED灯组的四幅不同偏振态全息图,并用四步相移法得到复振幅全息图,最后通过图像重建算法反演计算获得准确的再现图像。实验验证了基于α–BBO双折射晶体透镜的单次曝光自干涉全息成像方法的三维成像能力。

基于四波前横向剪切干涉的波前传感技术与应用(特邀)

高科技的发展对精密干涉成像提出了更高的要求。在现代光学和生物医学领域,无标记成像技术不依赖于传统的染料或荧光标记,进行3D活细胞原位观察和分析,促进定量相位显微术的发展。在光学检测技术领域,对于干涉系统的现场化、实时化的应用具有迫切需求,如激光波前的瞬态检测分析、高速流场检测、自适应光学的检测和控制、高精度光学系统像差分析等都迫切需要一个紧凑型、抗环境干扰、瞬态成像的干涉系统。为此,针对针对这些需求,全面介绍了四波前横向剪切干涉相位成像技术的原理、发展历程、波前重构方法以及其广泛的应用。四波前横向剪切干涉仪能够通过在一个单一的干涉图中获取两个正交剪切方向的四个剪切波前来实现瞬态相位成像,由随机编码光栅和相位棋盘组成新颖的四波干涉传感器(Four-wave Interferometric Sensor,FIS4)。FIS4干涉传感器凭借其独特的优势,如紧凑性、鲁棒性、高时间分辨率以及与现有显微系统的兼容性,在生物医学、光学测量、材料表征等众多领域展现出广阔的应用前景。这一技术的发展不仅为相关领域提供了新的研究工具,也为跨学科的创新和发现开辟了新的可能性。

基于跟踪误差约束的机器鱼抗扰动路径跟踪控制

为了解决机器鱼在扰动下跟踪效率低的问题,本工作提出了一种抗扰动和自适应的误差约束控制方案。首先,通过设计虚拟控制输入,并利用积分环节更新了自适应视线制导律,消除了侧滑导致的运动位置偏离,增强了机器人的抗干扰能力。其次,通过构造机器鱼的偏航和浪涌自适应控制器,使神经网络函数拟合模型的不确定项和水流扰动,并用逼近值补偿系统的控制输入。这提升了机体的环境适应性。最后,利用障碍Lyapunov理论,机器鱼跟踪位置和角度的一致最终有界性被证明。通过模拟和实验,与经典制导方案相比,所提方案提高了机器鱼的跟踪效率和稳态性能,使机器鱼的位置误差收敛速率平均提升了14.57%。

50 Gbit/s前传光模块关键技术研究与应用展望

随着全球5G网络的规模化商用及移动互联网流量的迅猛增长,更为丰富的无线频谱资源得以释放,高速率光模块在无线前传网络中的需求日益凸显。聚焦于50 Gbit/s前传光模块的关键技术,深入剖析了前传网络的两种主要组网方式,分析了前传链路的典型传输距离及链路损耗情况,探讨了10 km场景下粗波分复用(coarse wavelength division multiplex,CWDM)中各波长的最大色散值和最小色散值,并研究了相应的色散补偿策略,通过实验验证了不同多径干扰(multi-path interference,MPI)强度下系统光功率代价的变化,详细分析了多径干扰噪声对系统误码性能的潜在影响,为前传光模块参数的优化提供了重要的理论依据。此外,深入研究了50 Gbit/s前传光模块的光电芯片技术方案,对多种不同类型光模块的参数性能进行了严格的测试,提出了针对50 Gbit/s前传光模块光电接口参数的标准化建议,详细介绍了当前50 Gbit/s前传光模块在国内外的标准现状,并展望了未来应用的发展趋势。

分布式多基无源雷达信号级协同目标定位技术

利用空间已有电磁信号,采取分布式无源协同探测手段对目标进行零功率静默侦察,可有效提升我方雷达的低截获和抗干扰性能,是多雷达协同探测技术领域重点发展方向之一。目前,无源协同定位主要面临着目标回波弱、非合作外辐射源参数未知、直达径干扰等挑战。针对上述问题,文中提出了一种分布式多基无源协同的信号级高精度目标定位方法。该方法通过联合多基无源雷达双通道接收信号,建立信号级目标位置估计问题,以实现联合直达波干扰抑制和外辐射源及目标位置高精度估计,形成分布式多基无源雷达的零功率静默协同探测能力。此外,采用序贯估计策略和交替迭代估计策略将高维估计问题降低为多个低维估计问题,以降低算法的计算复杂度,强化实时定位能力。仿真结果表明,相较传统数据级定位,所提信号级方法在低信噪比和直达波干扰环境中表现出更好的定位性能。该无源协同定位方法可用于无人机前突静默侦察、反低空突防、反隐身等探测场景,能显著提升对敌目标的监视和打击效果。

Optimization of extreme ultraviolet vortex beam based on high harmonic generation

In high harmonic generation(HHG),Laguerre–Gaussian(LG) beams are used to generate extreme ultraviolet(XUV)vortices with well-defined orbital angular momentum(OAM),which have potential applications in fields such as microscopy and spectroscopy.An experimental study on the HHG driven by vortex and Gaussian beams is conducted in this work.It is found that the intensity of vortex harmonics is positively correlated with the laser energy and gas pressure.The structure and intensity distribution of the vortex harmonics exhibit significant dependence on the relative position between the gas jet and the laser focus.The ring-like structures observed in the vortex harmonics,and the interference of quantum paths provide an explanation for the distinct structural characteristics.Moreover,by adjusting the relative position between the jet and laser focus,it is possible to discern the contributions from different quantum paths.The optimization of the HH vortex field is applicable to the XUV,which opens up a new way for exploiting the potential in optical spin or manipulating electrons by using the photon with tunable orbital angular momentum.

深海环境下利用单矢量传感器估计目标深度

针对深海环境下目标的深度估计问题,本文研究了可靠声路径下直达波和表面反射波形成的周期性干涉调制模式。提出了一种利用单矢量传感器结合周期干涉调制结构对目标深度估计方法。依据矢量传感器接收到的声场信号构建周期干涉调制结构,利用水平复声强和垂直复声强获得目标的垂直到达角,通过周期干涉调制结构同目标深度之间的关系估计目标的深度。Bellhop数值仿真实验结果表明该方法能够有效估计目标深度,并且不需要精确的海洋环境知识。

基于光学干涉原理的温度传感研究(特邀)

提出一种基于光学干涉原理的温度传感器。通过在参考光路中引入单模光纤产生高斯光束;在测量光路中引入光纤光栅结构,使入射光通过光纤光栅、准直器产生平行的高斯光束,经螺旋相位板产生带有轨道角动量的拉盖尔-高斯光束,两束光将在合束器上发生干涉,产生螺旋式干涉图像。在测量光路中引入光纤光栅结构,主要是利用光纤光栅的光延迟特性。当环境温度变化时,光在光纤光栅中的传播产生相位延迟,导致测量光路和参考光路之间相位差发生变化,使螺旋干涉图像发生旋转。通过高分辨率相机实时检测干涉图像的变化,并对干涉图像进行图像处理,准确提取干涉图像的变化信息。通过上述方法,使传感器的温度灵敏度达到4.08°/℃,这将在温度传感领域具有重要的应用价值。

风-车-桥气动干扰作用下的汽车纵横向协调控制

为提高跨海大桥上轿车的风致行车安全能力,采用合成风和动网格耦合方法建立了轿车超越集装箱货车的瞬态分析模型,揭示了“风-车-桥”气动交互作用机理及其对轿车气动特性的影响规律。采用五次多项式插值算法建立了超车轨迹规划模型,基于模糊逻辑的双PID控制方法与径向基神经网络的滑模控制方法设计了纵横向协调控制器,开展了轿车超车过程的路径跟踪能力分析及行驶稳定性评价。研究结果表明:风-车-桥的气动干扰大小与行驶车道及位置有显著关系,纵横向协调控制器的路径跟踪控制精度和鲁棒性较好,轿车侧风稳定性提高效果明显。

基于改进快速搜索随机树算法的复杂机电产品线缆装配路径求解

针对复杂机电产品线缆装配路径求解困难的问题,提出一种基于改进快速搜索随机树算法的线缆装配路径求解方法.首先构建基于Cosserat弹性杆理论的线缆物理属性模型;然后提出改进快速搜索随机树算法的3种策略:基于人工势场法(artificial potential field,APF)的线缆装配路径规划策略,使线缆装配路径连接线缆目标构型,方便线缆实际装配;考虑线缆最佳离地高度的节点扩展策略,防止线缆因自身重力而与零部件产生碰撞干涉;基于非均匀三次B样条曲线的路径优化策略,求出一条相对平滑的路径.在Matlab线缆装配路径地图中对所提方法进行仿真的结果表明,改进后的快速搜索随机树算法的结果更优;并通过某相控阵雷达中的线缆装配路径实例,对该方法进行了验证.

基于人工智能高效近场扫描的瞬态强电磁干扰传导耦合路径可视化

在高压电子系统中,瞬态强电磁干扰会通过空间辐射、传导耦合等方式影响低压控制区的正常工作,在该工况下系统的电磁兼容问题较为突出。该文在时域电流测试与近场扫描结合的基础上,提出了一种改进的人工智能近场扫描算法,可实现强瞬态电磁干扰下传导耦合路径的高效可视化,据此采取了相应的整改措施并解决了系统中的电磁干扰问题。与传统近场扫描方法相比,该文提出的人工智能算法可大幅度提高测试效率。此外,还分析了不同参数的选择对该人工智能算法稳定性的影响,提出了一种自动停止扫描的判决标准,该判决标准使人工智能近场扫描算法不需要人为干预,从而具有更高的智能化与鲁棒性。

高频辅助变流器斩波电路共模谐振分析及抑制方法研究

文章针对高频辅助变流器共模谐振的分析与抑制方法展开研究,提出了一种高效的共模等效建模方法。首先将“多噪声源”的变流器系统等效成多个“单一噪声源”模型,显著降低了系统的复杂度,便于分析特定噪声源产生的谐振。其次分析了高频辅助变流器斩波电路共模电流的时频特征和干扰耦合路径的转移导纳特性,揭示了共模谐振的产生机理。最后提出了一种从源头抑制谐振的方法,并通过仿真与试验验证了抑制方法的有效性。

一种六轴机器人的铣削环境建模与仿真方法

论文首先以Mastercam强大且成熟的数控刀轨迹生成和后处理能力得出相应工件的加工刀轨迹文件,通过刀轨迹文件得出各个加工点与对应工件坐标系的位姿关系;其次,以FANUC机器人加工蜜胺脂勺子为例建立机器人加工环境,在加工环境中建立坐标系并分析相应坐标系之间的关系;最后在CoppeliaSim中建立机器人仿真模型进行仿真,在Cop-peliaSim软件中调用脚本程序实时分析加工运行过程中刀具轨迹点距离工件的最短距离,并将最短距离信息进行统计分析。论文提供的方法可以将数控加工程序文件转换成相应的机器人关节文件,同时建立相应的加工场景,联合仿真结果表明可生成无干涉的轨迹并具有较高的加工精度。

弗兰克-赫兹实验理论曲线推导

弗兰克-赫兹实验中的板极电流的理论预测模型亟待建立,现有相关理论工作侧重于对实验结果的分析和阐释,而少数理论计算模拟的工作或未展现理论曲线全貌,或运算耗时较长.本文基于两条引理和三条假设,将解析与编程结合,在1秒内给出理论曲线全貌,并分析其与实验值偏差的原因,据此引入电子运动轨迹和通过率修正,给出修正曲线全局预测,其与实验结果的符合度较高.这不但检验了玻尔理论的正确性,也表明理论成果可用于一定范围内板极电流的预测.