光生伏打LiNbO_3:Fe晶体从自散焦到等效“自聚焦”的动态转换

实验研究了在一定条件下LiNbO3:Fe晶体中从自散焦到等效“自聚焦”转换的动态行为 ,提出了出现自聚焦的物理机理为双相位共轭的法布里 珀罗干涉腔中的多光束干涉与光折变效应的共同结果 .该效应有希望在光折变自散焦介质中形成亮空间孤子     

基于自相位调制效应的硅基中红外全光二极管

信号单向导通器件是集成光学中一种重要的基本元件,而中红外波段在空间遥感,光谱分析等领域都有极其重要的应用.本文提出了一种由两个硅基微环谐振腔构成,基于自相位调制效应的硅基中红外全光二极管,并利用数值模拟的方法进行了分析.结果表明,在输入光强为0.5 mW到20 mW之间时,其非互易导通率可以大于20 dB,且正向透过时损耗小于10 dB.此外,本文还讨论了环形谐振腔中的线性吸收率,以及双稳态效应对结果的影响.     

Quantitative analysis of the self-absorption and reemission effects on the emission spectrum of photoluminescence in right-angle excitation–detection configuration

A theoretical approach based on differential radiative transport is proposed to quantitatively analyze the selfabsorption and reemission effects on the emission spectrum for right angle excitation–detection photoluminescence measurements,and the wavelength dependence of the reemission effect is taken into account.Simulations and experiments are performed using rhodamine 6G solutions in ethanol as model samples.It is shown that the self-absorption effect is the dominant effect on the detected spectrum by inducing pseudo red-shift and reducing total intensity;whereas the reemission effect partly compensates for signal decrease and also results in an apparent signal gain at the wavelengths without absorption.Both effects decrease with the decrease in the sample concentration and the propagation distance of the emission light inside the sample.We therefore suggest that diluted solutions are required for accurate photoluminescence spectrum measurements and photoluminescence-based measurements.     

激光超衍射加工机理与研究进展

随着纳米科技和微纳电子器件的发展,制造业对微纳加工技术的要求越来越高.激光加工技术是一种绿色先进制造技术,具有巨大的发展潜力,己广泛应用于不同的制造领域.为实现低成本、高效率、大面积尤其是高精度的激光微纳加工制造,研究和发展激光超衍射加工技术具有十分重要的科学意义和应用价值.本文首先阐述了基于非线性效应的远场激光直写超衍射加工技术的原理与国内外发展状况,包括激光烧蚀加工技术、激光诱导改性加工技术和多光子光聚合加工技术等;然后介绍了几种基于倏逝波的近场激光超衍射加工技术,包括扫描近场光刻技术、表面等离子激元光刻技术等新型超衍射激光近场光刻技术的机理与研究进展;最后对激光超衍射加工中存在的问题及未来发展方向进行了讨论.     

非相干非线性光学理论方法及其进展

文章主要综述了非相干非线性光学的几种理论方法,包括互相干函数法、相干密度法、自洽模理论、Wigner转换法、近似射线光学法和热动力学法等.其中,着重阐述了近期发展起来的理论方法——热动力学法,并对其原理进行了概括.对这几种理论方法的理解和探讨对非相干非线性光学效应的研究具有很重要的指导意义,有利于非相干非线性光学理论的进一步发展和完善.     

Preparation and Size Characterization of Silver Nanoparticles Produced by Femtosecond Laser Ablation in Water

Femtosecond laser ablation of silver plate placed in water is used to produce nanoparticle suspension. The method is easy to operate and the suspension is relatively stable. The optical properties and the size distribution of the suspension are studied with UV-vis absorption spectroscopy and dynamic light scattering, respectively. The shape of the nanoparticles is investigated by an atomic force microscope, which is near spherical. There are two kinds of nanoparticles, small particles with diameter about 35 nm, and large particles with diameter about 120 nm.     

Characterization of Photon Statistical Properties with Normalized Mandel Parameter

Normalized Mandel Parameter （Q） is introduced as a new measurement oi photon statistics. Dependences of Mandel parameter Q and corresponding normalized Mandel parameter （Q） on photon-counting time interval are experimentally investigated for pseudo-thermal light. We demonstrate that （Q） is more appropriate than Q, to measure the statistical deviation from Poisson distribution, because （Q） presents clearly both the intrinsic statistical properties and measuring effects. The advantages of （Q） in charactering nonclassical emissions are also discussed.     

基于瞬态光克尔效应的超快光学快门技术

系统介绍了几种基于瞬态光克尔效应的超快光学快门技术,包括传统的光克尔双折射快门技术,瞬态光栅快门技术,以及利用瞬态克尔透镜效应的光学快门技术。这些技术都是在泵浦-探测的实验配置基础上,利用门控光对克尔介质折射率的瞬态调制导致的信号光的相位（偏振态）、传播方向或光束发散角等光学特性的改变实现对信号光的超快时间分辨测量。对比讨论了这些超快快门技术的工作原理和实验配置,结果表明瞬态光束偏折快门技术相比其他快门技术具有无偏振配置要求、无相位匹配条件、超宽带光谱响应范围的特点,在光与物质相互作用的超快动力学研究中具有更为广阔的应用前景。     

Luminescent Enhancement in Mg- and Er-Codoped LiNbO3 Crystals

We investigate the MgO codoping-induced effect on the luminescent properties of Er^3 -doped and Er/Mg codoped LiNbO3 crystals. The emission and excitation spectra and the absorption spectra are measured. The results show that the luminescent behaviour of Er^3 ions is very sensitive to the codoping of Mg^2 ions. According to the photorefractive level theory, we propose a quench model for the Er/Mg codoped lithium niobate crystal. The quench centres are suggested to be the bipolaron (NbLi-NbNb), we attribute the luminescent enhancement to the decreasing concentration of these centres. The luminescent enhancement effect is successfully explained.     

光折变Fe:LiNbO3晶体中质子与热激发电子之间的竞争

研究了Ｆｅ：ＬｉＮｂＯ３晶体的光折变性能随晶体温度变化的动态性质,实验结果显示,质子与热激发电子之间存在着强烈的竞争,在较低的温度下（低于１２０℃）,在晶体光折变响应时间内,质子对晶体的光折变性能的很小,而电子的热激发速率Ｂ随晶体温度的变化将是影响晶体光折变性能的主要因素;而在较高温度时（高于１２０℃）,质子地迁移率的增大而开始显著地影响晶体的光折变性能。