17F和18Ne与质子的弹性散射角分布

采用逆运动学方法对放射性核束¹⁷F和¹⁸Ne与质子进行弹性散射实验,得到了实验测量微分截面.用较准确描述放射性核素性质的CH89参数化的光学势为初始光学势,用扭曲波玻恩近似的理论计算程序DWUCK4和自动参数搜索程序ABOD对实验数据进行光学势参数理论拟合,得到了与实验数据相符合的光学势参数.将得到的光学势参数进行分析,得到了17F和18Ne实势相互作用均方根半径分别为3.239fm和3.317fm.     

多级石英晶体旋光光学滤波器的滤波特性

根据石英晶体的旋光色散特性,利用光学矩阵方法对多级石英晶体旋光光学滤波器的滤波原理进行了详细的理论分析,推导出多级石英晶体旋光光学滤波器的透射主峰波长和通带半宽度的计算公式.利用分光光度计对单级和多级石英晶体旋光光学滤波器的滤波特性进行了实验研究,结果表明单级和多级石英晶体旋光光学滤波器滤波特性与理论曲线一致.从理论和实验上证明了多级石英晶体旋光光学滤波器与单级相比通带半宽度得到了有效的压缩,且随滤波器级数的增大,压缩的程度也随之增大. 关键词： 光学滤波器 偏振 石英晶体 旋光色散     

可控制光学双阱实验及非对称双阱的应用

根据用相位板产生可控制光学双阱的实验方案,制作了具有不同相位差的相位板,测量了不同相位差相位板衍射光强分布和从双阱到单阱演变过程中的衍射光强分布,得到了理论与实验一致的结果.进一步分析实验结果发现:相位差△ψ≠π的相位板,产生非对称光学双阱,在原子光学实验中也有很重要的应用,从而拓展了光学双阱在原子光学实验中的应用范围.     

基于Origin的波动光学实验仿真

以光的干涉、衍射实验为例,介绍利用Origin软件实现光学实验仿真的方法.该方法避免了复杂的编程,易学易用,实现过程简便.其逼真的仿真图样与光强分布曲线,为光学的理论分析与实验教学提供便利,可以引导学生开展探究性学习,加深对光学现象和规律的理解,从而提高教学质量.     

利用简单透镜组实现近轴光学隐身

利用简单透镜组实现近轴光学隐身的原理和方法,以4枚凸透镜完成了近轴光学隐身实验,并用计算机模拟了实验的光路图.讨论了选择不同焦距透镜组的优劣及透镜口径对实验的影响.该实验装置简单,可与透镜几何参量的测量实验相结合作为基础物理实验开设为面上教学实验.     

阿贝成像原理和空间滤波实验

"阿贝成像原理和空间滤波"是北京大学"普通物理实验"课程的传统实验,其目的是引导学生通过实验学习光学傅里叶变换以及空间频率、空间频谱和空间滤波等相关概念,探究光学成像和光学信息处理的基本原理、实验技术与方法.此实验涉及丰富的实验现象和物理与数学的综合知识,教学上颇具挑战性.本文利用显微成像的波动光学理论阐述阿贝成像原理,并配置相应的实验内容、技术方法和可以扩展的实际应用,希望从深度和广度上综合把握该实验的教学,以便引导学生的自主性实验探究.     

光学实验计算机仿真平台的构建

运用MAILAB构建了-个光学实验仿真平台,实现了包括基础光学中干涉和衍射、信息光学中的光学图像处理以及激光实验的仿真.并利用GUI设计了人机友好的图形用户界面,最后通过mcc编译生成可脱离MATLAB环境运行的可执行文件.该平台可移植性、可扩展性强,用户可直接进行实验项目的选取,实验参数的灵活设置以及实验结果的对比分...     

基于微波频差转换的光学拍频研究

光学拍频是大学物理和光学实验教学中的重要内容.由于激光器存在中心波长漂移问题,实验中不易产生可观测的拍频信号.受到微波光子技术中微波波段和光波波段相互作用机理的启发,提出了基于微波频差转换的光学拍频方法.借助强度调制和相位调制将两个频差较小的微波信号调制到同一光载波上,结合光学滤波器获得了两个频差极小的稳定光信号,利用光电探测器实现光学拍频,从仿真和实验两个层面分别获得了可视化的低频拍频信号.该研究为大学物理和光学实验提供了与科学前沿相结合的实验方案,可拓展教学内容和教学深度,有利于培养学生的科学素养.     

基于STEM的水质光学综合测量虚拟仿真实验

基于STEM理念,根据光学方法对水质折射率、浊度、表面张力、含氧量的物理测量原理,研发了水质光学综合测量虚拟仿真实验软件,运用Unity编程创立虚拟仿真场景,C#语言模拟实验操作与数据分析,LabVIEW展示实验采集.该软件可以自主选择光学元件搭建实验装置,动态展示实验现象,并快速采集、拟合、分析实验数据,最终完成对水...     

用串行迭代算法设计具有长焦深功能的衍射光学元件

提出一种串行迭代算法,将它用于控制波前传播进行衍射光学元件设计.用此算法设计出能使半导体激光束聚焦并具有长焦深功能的衍射光学元件.模拟计算结果表明了此设计方法的有效性.该衍射光学元件已用光刻和离子刻蚀技术制备并进行了光学实验研究,取得了与理论设计一致的实验结果.     

Atomic dipole traps with Amplified Spontaneous Emission: A proposal

We propose what we believe to be a novel type of optical source for ultra-cold atomic Far Off-Resonance optical-dipole Traps. The source is based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a high power Erbium Doped Fiber Amplifier. The main interest of this source is its very short coherence length, thus allowing an incoherent superposition of several trapping beams without any optical interference. The behavior of the superimposed beams is then a scalar sum greatly simplifying complex configurations. As an illustration, we report an estimation of the intensity noise of this source and an estimation of the additional atomic heating rate for an evaporative cooling experiment application. They are both found to be suitable for cold atoms experiments.     

用于实现散射介质中时间反演的数字相位共轭的相干性

抑制散射介质对光的散射,调控光在散射介质中的传输,是光通信、生物光子学、光镊等领域的重要课题.设计并实现了基于宽谱光源和数字相位共轭的可调控光在散射介质中传输的时间反演实验系统.实验获取了不同相干长度下物光和参考光束之间的光程差与干涉图样、相位图及时间反演信号之间的关系,分析了光源相干性对调控光在散射介质中传输的影响.实验结果表明,基于宽谱光源的相干特性和数字相位共轭技术,通过调节光程差能选择性获取同一散射角度及相同传输路径的光束的相对相位,再利用空间光调制器对参考光束进行调控,实现光束的反向传播,从而选择性实现对同一散射角度及相同传输路径的光的时间反演.     

Bit rate and pulse width dependence of four-wave mixing of short optical pulses in semiconductor optical amplifiers

We investigate the saturation properties of four-wave mixing of short optical pulses in a semiconductor optical amplifier. By varying the gain of the optical amplifier, we find a strong dependence of both conversion efficiency and signal-to-background ratio on pulse width and bit rate. In particular, the signal-to-background ratio can be optimized for a specific amplifier gain. This behavior, which is coherently described in experiment and theory, is attributed to the dynamics of the amplified spontaneous emission, which is the main source of noise in a semiconductor optical amplifier.     

Experimental realization of one-way quantum computing with two-photon four-qubit cluster states

We report an experimental realization of one-way quantum computing on a two-photon four-qubit cluster state. This is accomplished by developing a two-photon cluster state source entangled both in polarization and spatial modes. With this special source, we implemented a highly efficient Grover's search algorithm and high-fidelity two-qubit quantum gates. Our experiment demonstrates that such cluster states could serve as an ideal source and a building block for rapid and precise optical quantum computation.     

Phase-coherent light pulses for atom optics and interferometry

We have developed a novel source for the generation of powerful phase-coherent light pulses. Our setup uses an acousto-optic modulator (AOM) inside an external high-finesse resonator. By applying a short rf pulse to the AOM, we dump the cavity and extract a large part of the stored and enhanced power within a short optical pulse and with a controllable optical phase. In preliminary experiments we reached 100 W of peak power in a 15-ns optical pulse. The mutual phase coherence of successive light pulses is demonstrated with a molecular iodine interferometer experiment in a cell.     

高超噪比宽带毫米波噪声信号光子学产生研究

受电子器件工作频率及功率的限制,传统电子学方法产生的噪声源的超噪比通常小于20 dB,针对这一问题,本文提出了一种基于非相干光拍频产生高超噪比宽带毫米波噪声技术.首先,用两个光滤波器对宽带放大自发辐射光源进行滤波整形.将获得的两束频率不同的放大自发辐射光耦合进入光电探测器进行拍频,从而产生电噪声信号.理论分析发现,通过...     

Synthetic aperture laser optical feedback imaging using galvanometric scanning

We describe a new one-dimensional synthetic aperture imaging laser radar (ladar) using the resonant sensitivity of a microchip laser to frequency-shifted optical feedback and galvanometric scanning of the target under investigation. In our experiment, the laser is both the source and the detector, providing optical amplification with self-aligned heterodyne detection. By using galvanometric scanning, we achieve an along-track spatial resolution better than the diffraction limit.     

对白光干涉法测量透明介质折射率实验的探讨

在时域中求解得到,光路中存在色散介质的情况下,白光双光束干涉光强度.由此证明了:用白光干涉法测量得到的是白光在色散介质中的群折射率,而并非相关报道中认为的折射率;讨论了介质厚度及色散对于涉条纹的可见度和干涉条纹显现时动镜移动范围的影响.上述结论得到了实验验证.     

Research of an integrative technique with polarization modulation for generating high-quality multi-wavelength optical source

With the development of society, the need of fiber optical communication expansion and upgrades is increasing. Multi-wavelength optical source has been popularly researched as one of the key component of DWDM. A integrative technique with polarization modulation for high-quality multi-wavelength optical source has been proposed theoretically and experimentally. A comprehensive and systematic overview of how to get a high-quality multi-wavelength optical source, based on in-depth and detailed experiment research. It is found that the optical intensity of the sidebands are not only related to the microwave source and DC bias voltage loaded at EOIM, but also affected by the polarization state of the input light. Five perfect sidebands with equal peak value can be realized by regulating the polarization state of the input light, in addition to regulating the microwave source and DC bias voltage loaded at EOIM as well as. The peak–peak difference of intensity of sidebands can be down to 0.00 dBm in the best situation. Polarization state of the input light plays a good role in generating wonderful sidebands with equal space, balanced peak value, high signal-to-noise ratio. The number of sidebands can be selected according to specific application. The findings may have important implications for high-quality multi-wavelength optical source.     

All-fiber incoherent frequency-to-time mapping method for microwave signal generation with baseband transmission and multicasting support

We present a proof-of-principle experiment for achieving simultaneous distribution of baseband radio-frequency data and up-conversion with broadcasting support over a passive optical network. The technique is based on an incoherent frequency-to-time mapping method for pulse shaping. Specifically, we synthesize the spectral density function of sliced ASE noise from an EDFA with a periodic Mach–Zehnder fiber interferometer optical filter. By using external intensity modulation combined with propagation in an optical fiber, after photodetection, the resultant averaged temporal pulse profile resembles the shape of the incoherent source. The photodetected signal contains both the baseband data and an up-frequency converted copy with central wavelength for the microwave carrier into the ultra-wideband range and tuning capability by selection of the fiber length.