Controllable optical multi-well trap and its optical lattices using compounded cosine patterns

This paper proposes a flexible scheme to form various optical multi-well traps for cold atoms or molecules by using a simple optical system composed of an compounded amplitude cosine-only grating and a single lens illuminated by a plane light wave or a Gaussian beam.Dynamic manipulation and evolution of multi-well trap can be easily implemented by controlling the modulation frequency of the cosine patterns.It also discusses how to expand this multi-well trap to two-dimensional lattices with single-or multi-well trap by using an orthogonally or non-orthogonally modulated grating,as well as using incoherent multi-beam illumination,and these results show that all the symmetric structures of two-dimensional Bravais lattices can be obtained facilely by using proposed scheme.     

Laser guiding of cold molecules in a hollow optical fiber and continuous-wave cold molecular beam generation

A novel scheme for guiding arbitrary buffer-gas cooled neutral molecules in a hollow optical fiber(HOF) using a red-detuned HE 11 mode is proposed and analysed theoretically.We give the electromagnetic field distribution of the HE 11 mode in the HOF and calculate the optical potential of an I 2 molecule,and study the molecule guiding mechanism using a classical Monte Carlo simulation.Using a 6 kW input laser,an S-shape HOF with a 2 cm curvature radius for both bends,and an input molecular beam with a transverse temperature of 0.5 K and longitudinal temperature of 5 K,we obtain a guiding efficiency of ～0.126% for the scheme,and the transverse and longitudinal temperatures of the guided molecular beam are 1.9 mK and 0.5 K,respectively.     

几种压电陶瓷在极化时声发射特性研究

压电陶瓷是多畴压电材料,在极化之前从宏观上看并不显压电性;通过在直流电场中的极化可以使其电畴作定向排列,从而使陶瓷显压电性.采用声发射技术监测压电陶瓷极化时有无声发射产生和声发射的情况,可以掌握压电陶瓷在极化过程中电畴的动态特性;这对于研究压电陶瓷的电畴结构和极化工艺将是有益的。     

用线偏振光产生可调矢量椭圆空心光束

提出了利用π相位板产生矢量空心光束的新方案,两个偏振方向互相垂直的线偏振光波分别通过π相位板调制后进行强度叠加,得到椭圆空心光束,用矩形光阑调节相位板的几何尺寸,可以实时调节椭圆的离心率;调节π相位板的方位,能够实现径向矢量空心光束到角向矢量空心光束的转换。分析、讨论了方案的可行性和在原子光学中的潜在应用,结果表明:本方案在原子光学中有很好的应用前景。     

多模气体激光纵模线型函数及其频宽的实验观测

本文根据多模激光时间相干性ｇ（１）（τ）的准周期性特点，提出了一种观测多模激光纵模线型函数及其频宽的新方法－程差２ｋＬ法。文章介绍了测量原理与方法，并以双模Ｈｅ－Ｎｅ激光器为例，给出了相应的实验结果，研究表明，多模气体激光的纵模线型函数为洛仑兹（Ｌｏｒｅｎｔｚ）线型函数，相应的纵模频宽约为１０＾７Ｈｚ。     

基于数字信号处理技术的连续变焦镜头控制系统设计

针对以往连续变焦镜头控制系统存在的速度响应慢、准确度低等缺点,对连续变焦镜头及其控制系统的设计方法进行改进.采用机械补偿的变焦距镜头理论,确定变焦距系统位移曲线.基于数字信号处理技术和步进电机的控制技术,设计了包括数字信号处理器、步进电机、步进电机驱动器、键盘控制、计算机通信、液晶显示模块为一体的控制系统,同时对变焦距系统增加了自锁模块,提高了控制系统的安全性与可靠性.初步实验结果表明,控制系统准确度在0.01 mm以内,满足0.12 mm的设计指标.     

PYRAMIDAL-HOLLOW-BEAM DIPOLE TRAP FOR ALKALI ATOMS

We propose a dark gravito-optical dipole trap, for alkali atoms, consisting of a blue-detuned, pyramidal-hollow laser beam propagating upward and the gravity field. When cold atoms from a magneto-optical trap are loaded into the pyramidal-hollow beam and bounce inside the pyramidal-hollow beam, they experience efficient Sisyphus cooling and geometric cooling induced by the pyramidal-hollow beam and the weak repumping beam propagating downward. Our study shows that an ultracold and dense atomic sample with an equilibrium 3D momentum of ～3 \hbar k and an atomic density above the point of Bose-Einstein condensation may be obtained in this pure optical trap.     

关于傅里叶光学的描述问题(续)

三、二次相位信号法以上我们看到了用通常方法处理这类问题的基本特征。它基本上是,对菲涅耳—基尔霍夫衍射积分作傍轴近似,加上薄透镜的二次相位传递因子,反复计算菲涅耳变换积分,来求透镜和自由空间构成的光学系统的作用。另一方面,从信息传递的角度来看,任何一个器件,其输出都可写成输入与器件脉冲响应的卷积的形式。由前面我们看到,菲涅耳变换的核e~((jk)/(2d)ρ~2)就扮演着这种脉冲响应的脚色。这就表示可以把自由空间看作具有上述脉冲响应的一个器件。而透镜以及其他调制介质     

关于傅里叶光学的描述问题(续)

四、抽象向量法上述算符法虽然将某些运算作为算符来处理,并建立了一些算符之间的代数关系,但没有利用向量空间的概念。在下面的方法中,基于与量子力学的类比,明确地提出了一个抽象向量空间,从而将量子力学的方法移到傅里叶光学中来。 1.单色波传播方程的傍轴近似