基于琼斯法的高亮度积分球定标光源

针对目前光学口径不断增大的空间光学遥感器实验室辐射定标的需求,基于琼斯法设计了一种在400~900 nm波段积分辐亮度为6 800 W/(m2·sr)的高亮度积分球定标光源。对该光源的热设计表明:采用水冷散热的方式能够满足高亮度积分球定标光源的散热需求。实验表明,该定标光源在400~900 nm波段范围内积分辐亮度达到6 714 W/(m2·sr),经过散热后积分球球体温度场分布满足定标要求,可应用于工程实践。     

Generation and storage of double slow light pulses in a solid

We experimentally study the generation and storage of double slow light pulses in a Pr³⁺:Y₂SiO₅ crystal. Under electromagnetically induced transparency, a single signal pulse is stored in the spin coherence of the crystal. By simultaneously switching on two control fields to recall the stored information, the spin coherence is converted into two slow light pulses with distinct frequencies. Furthermore, the storage and controlled retrieval of double slow light pulses are obtained by manipulating the control fields. This study of double slow light pulses may have practical applications in information processing and all-optical networks. vspace2mm     

Absorption Spectra of a Three-Level Atom Embedded in a PBG Reservoir

We introduce the ‘decay rate＇ terms into the density matrix equations of an atom embedded in a photonic band gap （PBG） reservoir successfully. By utilizing the master equations, the probe absorption spectra and the refractivity properties of a three-level atom in the PBG reservoir are obtained. The interaction between the atom and the PBG reservoir as well as the effects of the quantum interference on the absorption of the atom has also been taken into account. It is interesting that two different types of the anomalous dispersion relations of refractivity are exhibited in one dispersion line. The methodology used here can be applied to theoretical investigation of quantum interference effects of other atomic models embedded in a PBG reservoir.     

Effects of transverse profile of pump field on second harmonic generation in periodic nonlinear materials

We report on a theoreticalanalysis of the effects of a converging pump field of Gaussian transverse profile on second harmonic generation in a periodic nonlinear material with quasi-phase-matching. The outputs of the centre intensity and the intensity flux for second harmonic generation are derived by simulation, based on the parameters of quasi-phase-mismatch, the waist and focus positions of the input pump beam. The results show that when the transverse profile of the pump field is taken into account, the quasi-phase-match value and focus position of input beam for maximal second harmonic generation flollow new criteria.     

线性共轭齐聚物共轭单元依赖的光学特性

研究三种线性共轭齐聚物(F-P、F-P-F和P-F-P-F-P)的光学特性,其中吩噻嗪单元(F)和芴单元(P)交替排列. 随着共轭体系的增强,它们的吸收和发射带都逐渐红移,双光子吸收特性明显的改进. 利用连续速率分布模型分析荧光动力学的结果显示,它们的弛豫速率在逐渐增加,速率分布宽度也在变窄. 量子化学计算给出了它们的分子结构和跃迁机制,显示π共轭系统的增强促使了双光子特性的改进.     

一种高亮度积分球定标光源的热设计EI北大核心CSCD

针对目前光学口径不断增大的空间光学遥感器对实验室辐射定标的要求,设计了一种使用近距离小面源照明方式定标的高亮度积分球光源,并对该光源的光学参数和结构参数进行了详细设计。为了解决高亮度积分球使用时的散热问题,采用水冷的散热方式,设计了专门的散热管路。对该光源循环水流速0.1 m/s下利用有限元分析法热仿真分析,仿真结果表明,溴钨灯光源附近温度维持在125°C左右,积分球出光口温度维持在80°C左右。实验结果表明,溴钨灯光源附近温度维持在125°C左右,积分球出光口温度维持在100°C左右。通过对比分析了积分球出光口温度差异的原因,验证了仿真分析与理论计算的正确性。同时测试了该光源在400~900 nm波段范围内光谱辐亮度为6714 W/（m2·sr）。     

Spontaneous emission spectrum of a four-level atom in a double-band photonic crystal

The spontaneous emission spectrum from a four-level atom in a double-band photonic crystal has been investigated.We use the model which assumes three atomic transitions. One of the transitions interacts with the free vacuum modes,and the other two transitions couple to the modes of the isotropic photonic band gap (PBG), the anisotropic PBG and another free vacuum. The effects of the fine structure of the lower levels on the spontaneous emission spectrum of an atom are investigated in detail in the three cases. New features of four (two) transparencies with two (one) spontaneous emission peaks, resulting from the fine structure of the lower levels of an atom, are predicted in the case of isotropic PBG modes.     

物理类在线开放课程群的建设展望与建设理念的思考

简要回顾了在线开放课程及课程群的发展背景,论述了在新形式下充分利用互联网等现代化平台进行大学物理教学改革、系统构建物理类在线开放课程群的必要性.在线开放课程群具有服务主体清晰、课程系统、资源优质等精品优势特征.作者进一步探讨了在线开放课程群建设中应着重突出的教学理念,即在充分理解物理学及其课程体系的逻辑性、发展历程的基础上,以高质量教学内容的构建为核心,以培养学生能力、提升学习兴趣为目标的教学理念.最后提出了作者对于课程群建设内容重点的思考及建议.     

不同极性溶液中MEH-PPV链内激子扩散的研究（英文）

本文采用飞秒时间分辨瞬态光栅技术研究了MEH-PPV在不同极性溶液中的内激子扩散行为.采用宽带连续白光同时探测瞬态吸收和瞬态光栅信息.系统地研究了MEH-PPV的振动失相行为以及单激子弛豫和粒子数弛豫动力学.结果表明,在极性较大的溶剂中,样品溶液的弛豫扩散过程会加快.