用卡尺测定透明液体和固体的折射率

媒质的折射率是光学中的一个重要参数。在现行的中学物理教材中介绍的测定水的折射率的实验方法实际上难以进行。因为直尺在水下部分经折射所成的像清晰可见,而在水上部分经反射在水中的像却暗淡难辨,观察及读数十分困难。本文介绍的方法用薄铁片制成的两测量脚,粘在卡尺上(如图1所示)来测定水的折射率,则克服了这一障碍,用于测定玻璃的折射率也比插别针的方法更显得简便、准确。     

Nd:YAG纳米粉体的制备和光谱性质

采用共沉淀方法，以碳酸氢铵（NthHC03）为沉淀剂制备得到Nd：YAG前驱物，将其在不同的温度下煅烧并采用红外光谱（FT-IR）、X射线衍射（XRD）、透射电镜（TEM）、荧光光谱分析等技术对样品进行了表征。在900～1000℃下煅烧前驱物，出现YAP和YAM中间相并对共沉淀法中间相出现的原因进行了分析；获得纯YAG晶相的煅烧温度为1100℃，晶粒粒度分布约为40～80nm，具有良好的分散性。光谱研究表明Nd：YAG纳米粉体的发光性能良好，其红外光谱及荧光光谱与单晶无明显的差异。     

纠缠态的红外双光子场

1纠缠态的量子粒子 光子具有几乎不与它周围的所有透明物体发生作用的优越性能，光能够通过棱镜或光导纤维并且能保持它的相干性不变．因此，在室温下也同样能导向奇异光子量子态的这一过程，而不需要采取更进一步的隔离措施以免受到周围环境的影响．红外光子对就是从某些非线性光学晶体的、经过紫外线光子处理过的参量荧光中自发地产生的，如图1所示．     

透明导电铟铋氧化物薄膜的制备及其性能

以氧化铟为主体材料,以铋为掺杂材料,采用真空热蒸发方法研制出2.5%铋掺杂的透明导电氧化物薄膜(IBO)。实验表明:IBO薄膜具有良好的表面形貌,载流子浓度为3.955×1019cm-3,载流子迁移率达到50.21cm2·V-1·s-1,电导率为3.143×10-3Ω·cm,在可见光范围内的平均透过率超过82%,功函数为4.76eV。采用其作为阳极制作的OLED得到最大亮度30230cd/m2,最大电流效率为5.1cd/A。结果表明IBO是一种良好的光电器件阳极材料。     

基于数字图像相关的透明材料厚度测量

提出了一种测定透明材料厚度的新方法。该方法是基于透明材料对光的折射特点,利用光斑点面内位移与材料厚度的变化关系,将厚度的测量转化为对面内位移的测量。将此方法与数字图像相关法相结合,实现了单摄像机对厚度的测定。对轴向拉伸状态下的有机玻璃板的厚度变化进行了测定,将实验结果与理论值进行了对比,两者符合较好,证明了该实验方法的有效性和可行性。     

Enhancement and Suppression of Four-Wave Mixing in a Four-Level Atomic System

We report observations of the enhancement and suppression of four-wave mixing （FWM） in an electromagnetically induced transparency window in a Y-type ^85 Rb atomic system. The results show the evolution of the dressed effects （from pure enhancement to partial enhancement/suppression, and finally into pure suppression） in the degenerate-FWM processes. Moreover, we use the perturbation chain method to describe the FWM process. Finally, we observe the polarization dependence of the enhancement and suppression of the FWM signal.     

射频驱动下电磁诱导透明窗口的分裂和增益的出现

在Λ型三能级系统的基础上引入两个共振射频场, 通过详细讨论系统的探测吸收特性随两个射频场Rabi频率取不同值时的变化规律, 得出电磁诱导透明(EIT)的分裂规律以及EIT上出现增益现象的产生条件.研究结果表明: 两个射频场对系统所起的控制作用不同, 控制基态精细结构能级之间跃迁的射频场对EIT的分裂起作用, 而控制激发态精细结构能级之间跃迁的射频场不会导致EIT的分裂; 而且, 只有当控制基态精细结构能级之间跃迁的射频场的Rabi频率大于控制激发态精细结构能级之间跃迁的射频场的Rabi频率时, 才能产生EIT与增益相叠加的新特性. 关键词： 射频场 电磁诱导透明 增益 精细结构能级     

Storage and retrieval of ultraslow optical solitons in coherent atomic system

We investigate the propagation of intense probe pulses in a lifetime broadened Λ-type three-level atomic system with a configuration of electromagnetically induced transparency. We find that ultraslow optical solitons formed by a balance between dispersion and nonlinearity can be stored and retrieved in the system by switching off and on a control field. Such pulses are robust during storage and retrieval, and hence may have potential applications in optical and quantum information processing.     

Linewidth of electromagnetically induced transparency under motional averaging in a coated vapor cell

The linewidth of electromagnetically induced transparency(EIT) in a coated Rb vapor cell was studied under a magnetic field gradient.The nonlinear broadening of the EIT linewidth with the magnetic field gradient was observed.It was found that the motional averaging of the field gradient was more pronounced at higher laser intensities and larger beam sizes.In the same regime,there was a small linewidth decrease with the increasing magnetic field gradient.We have established a Monte-Carlo model,which gave results in good qualitative agreement with our experiment.Physics pictures for the above phenomena were also suggested.These results provide an understanding of the EIT linewidth behavior under motional averaging,and should be useful for applications in quantum optics and metrology based on coated vapor cells.     

The metamaterial analogue of electromagnetically induced transparency by dual-mode excitation of a symmetric resonator

Electromagnetically induced transparency （EIT） is obtained in a symmetric U-shaped metamaterial, which is at- tributed to the simultaneously excited dual modes in a single resonator under lateral incidence. A large group index accom- panied with a sharp EIT-like transparency window offers potential applications for slowing down light and sensing.