Er~(3+)掺杂玻璃腔内增强激光冷却理论分析

近年来,掺Er3+的CdF2-CdCl2-NaF-BaF2-BaCl2-ZnF2玻璃已成为固体材料激光冷却领域中新的研究材料之一.本文利用激光器输出理论和驻波腔内共振增强原理分析了该材料的两种腔内增强激光的冷却,计算结果表明腔增强可获得几十到几百倍的增强因子.此外,比较了内腔和外腔这两种增强方案,研究结果表明,当材料的吸收比较小时,特别是材料长度小于0.3 mm时,采用内腔增强方案,腔内抽运功率高,冷却材料对激光的吸收大.然而当材料的吸收比较大时,特别是材料长度大于3 mm时,外腔增强方案更具优越性.最后,根据Er3+掺杂材料制冷工作波长和功率的要求,指出腔增强实验可通过半导体激光器来实现.     

Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.     

Electrostatic surface trap for cold polar molecules on a chipElectrostatic surface trap for cold polar molecules on a chipElectrostatic surface trap for cold polar molecules on a chip

We propose a simple scheme for trapping cold polar molecules in low-field seeking states on the surface of a chip by using a grounded metal plate and two finite-length charged wires that half embanked in an insulating suhstrate, calculate the electric field distributions generated by our charged-wire layout in free space and the corresponding Stark potentials for ND3 molecules, and analyze the dependence of the trapping center position on the geometric parameters. Moreover, the loading and trapping processes of cold ND3 molecules are studied by using the Monte Carlo method. Our study shows that the loading efficiency of the trap scheme can reach 11.5%, and the corresponding temperature of the trapped cold molecules is about 26.4 inK.     

玻色-爱因斯坦凝聚(BEC)实验及其最新进展

近年来,有关玻色-爱因斯坦凝聚(BEC)的实验研究得到了快速发展,并取得了一系列重大的实验进展。本文重点介绍了玻色-爱因斯坦凝聚的实验结果及其最新进展,主要包括具有正、负散射长度碱金属(7Li,23Na,41K,85Rb,87Rb和133Cs)原子BEC的实现,自旋极化1H原子、亚稳态4He原子和具有2个价电子的174Yb稀土原子BEC的实现,全光型BEC和微阱BEC乃至低维BEC的实现,甚至分子BEC和费米原子对的凝聚以及超冷BEC凝聚体的应用等。     

A novel controllable double-layer magnetic lattice with cold atoms

We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magneto optical traps (MOTs) and Ioffe traps can be constructed by using same wire configurations and different currents and bias fields. Furthermore, the array of double-well magnetic microtraps can be continuously evolved as an array of single-well magnetic microtraps by reducing the currents in the wires. Our study shows that our scheme can be used to realize a controllable double-layer magnetic lattice with cold atoms, to form array of Bose-Einstein condensations (BECs), or to study atom interference, and so on.     

自由运转双模He—Ne激光场g（2）（τ）的时谱特性及其可能应用

采用光场的量子理论导出了双模Ｈｅ－Ｎｅ激光场二阶相干度ｇ（２）（τ）的时谱公式，讨论了ｇ（２）（τ）的周期性，时谱特性和光子反相关效应，并在分析其频率调谐特性的基础上，探讨了双模激光场ｇ（２）（τ）的时谱特性在双模激光线宽△ｖＤ的测量和双模激光稳频稳幅中的可能应用。     

对二氯苯喇曼谱用于激光喇曼分光计中杂散光的半定量测试

本文详细研究了近波数区(20cm~(-1)附近)对二氯苯喇曼谱峰背比与激光喇曼分光计中杂散光的定量关系,并在此基础上提出了一种测试激光喇曼分光计中杂散光的半定量方法。     

关于傅里叶光学的描述问题

一、引言自从1960年激光器问世后,人们获得了新的相干光源,从而得以更有效地将通信理论应用于光学系统的分析与综合,并逐渐形成了一个新的光学分支,叫作傅里叶光学。目前,傅里叶光学的概念与方法已在很多工程与科学领域得到日益广泛的应用。在傅里叶光学中,为了分析与综合各种光学系统,就要对诸光学元件或一个光学系统的诸部分进行计算。这就需经常计算菲涅耳-基尔霍夫衍射积分。如果系统所包含的元件较多,或者要处理起不同作用的几个系统的级联时,计算这些积分就相当麻烦,从而给分析与     

亚微米局域空心光束的产生及其在单原子囚禁与冷却中的应用理论研究

提出了一种采用单模光纤、环形二元相位板和微透镜组成的光束整形系统产生亚微米局域空心光束的方案. 根据瑞利-索莫菲衍射积分公式, 数值计算了微透镜焦平面附近的场分布, 详细研究了空心光束的暗斑尺寸与单模光纤模场半径和微透镜焦距的关系. 数值计算结果表明: 在微透镜焦平面附近光场分布近似对称, 在焦点处场强近似为零, 周围场强逐渐增大, 形成半径约为0.4 μm的三维封闭的球形空心光场区域, 即亚微米局域空心光束. 当局域空心光束为蓝失谐时, 光场中的原子将被囚禁在光场最弱处. 若加上抽运光, 原子将受到蓝失谐局域空心光束与抽运光共同激发的强度梯度Sisyphus冷却. 本文利用该方案产生的亚微米局域空心光束构建单原子的囚禁与冷却器件, 并以单个⁸⁷Rb原子为例, 利用Mont-Carlo方法研究亚微米局域空心光束中单原子囚禁与强度梯度冷却的动力学过程, 结果表明利用该器件可以获得温度在5.8 μK量级的超冷单原子.