从电动力学到量子电动力学：纳米光电子器件

纳米尺度下的光电器件的研制与米、毫米、微米尺度下电子器件或光学器件的研制在基本原理与制造技术上有本质的不同。必须采用量子电动力学和介观物理作为基本原理。在量子电动力学中,光子与电子可以相互转化,光子也可以储存在“空腔”中。光一电转换或光一电一光的转换甚至可以在远小于一个光波的尺度内实现（如100nm以下）。基于大量最新现象发现的启示与推动,产生了一种全新的光予技术：纳米光子技术。在这种全新的纳光子技术中,人们将光子电子的输运与转化联合起来进行考虑,非线性光学获得了长足的发展。微电子技术和概念被大量地推广应用于纳光子技术开发。创新型元件如集成激光器、30dB光放大器、效率为30％的1．55μm滤波器等层出不穷地涌现。纳米技术的研发为信息储存、输运和处理开辟了新的天地。进入21世纪,纳米光子技术研究日新月异。在摩尔经验规律的指导下,不断发展的微电子工业的制造精度已进入100nm领域。大规模应用纳米电子、纳米光子技术的时代已经来临。一些新型的光通讯线路已开始应用纳米光子器件。对公众而言,用于照明的LED只是一个应用实例。报告将结合法国国家纳米研究平台的研发成果来阐述纳米光子学的原理和纳米光子器件发展的趋势。     

Particle sizing by time-resolved Mie calculations—A numerical study

If a small transparent particle is illuminated with a short laser pulse, the signals of the individual scattering light orders appear temporally successively. Since to each scattered light order belongs a specific optical path through the particle, the particle size can be determined from the time difference between the detected scattered light signals. For the case of a detector position within the backscatter region, which especially is important in measuring practice, the time difference between the specular reflection signal and the signal after a single internal reflection (refraction of second order) must to be evaluated. In the numerical simulation we generate the concerned scattered light signals by using time-resolved Mie calculations and in this paper we present the geometrical models, which permit a correct interpretation of the temporal behavior of these pulse-induced scattered light signals.     

激光诱导熔石英表面损伤修复中的气泡形成和控制研究

基于熔石英材料在CO_2激光作用下的温度分布和结构参数变化的计算结果,对熔石英损伤修复中的气泡形成和控制进行了研究.针对损伤尺寸介于150—250μm之间的损伤点,提出了一种能够有效控制气泡形成的长时间低温预热修复方法.基于低温下熔石英材料结构弛豫时间常数较长的特点,该方法在不引起熔石英材料结构发生显著变化的同时,能够解吸附表面和裂纹处所附着的气体和杂质,可有效降低裂纹闭合过程中气泡形成的概率.实验结果表明,长时间低温预热修复方法的成功修复概率可达到98%.     

2.0μm附近模拟呼吸气体中~(13)CO_2/~(12)CO_2同位素丰度的高精度实时在线测量

采用可调谐二极管激光吸收光谱技术,结合一新型多通池搭建了一套模拟呼吸气体中CO_2同位素丰度的测量装置.气体的压强、温度和流速被很好地控制且均能保持长期的稳定性;采用三次多项式拟合光谱基线,对光谱进行归一化,很好地消除了功率变化对测量结果的影响;利用移窗-回归技术消除频率漂移对同位素丰度测量的影响.实验结果表明:移窗-回归法的引入不仅延长了系统的稳定时间,还提高了系统的测量精度;小波去噪的应用获得了比多光谱平均法高2倍的信噪比;系统的稳定时间为100 s;Kalman滤波后系统测量精度为0.067‰.     

中国高功率固体激光技术发展中的两次突破

高功率固体激光是激光聚变、高能量密度物理与前沿基础科学研究必需的实验手段。上世纪六七十年代,老一辈科学家王淦昌、王大珩、邓锡铭、于敏等人以敏锐的科学洞察力与超前的战略眼光,开创了中国激光聚变研究的宏伟工程,为中国高功率固体激光技术的长远发展注入了强劲的东风。中国工程物理研究院(简称中物院)作为激光聚变研究的总体单位,联合中国科学院等国内优势单位,在国家强有力的支持下,推动与组织了中国高功率固体激光技术与装置研制的快速发展。中物院激光聚变研究中心作为高功率固体激光技术研发的总体单位之一,敢于担当、勇于创新,团结协作,坚持三十余载,实现了中国高功率固体激光技术研发历程中的两次“突破”,即突破新一代高功率钕玻璃激光技术,相继研制成功了亚洲规模最大、技术先进的神光-Ⅲ原型装置和神光-Ⅲ激光装置;突破百太瓦超短超强激光关键技术,建成了国内首台输出能力高达200 TW的SILEX-Ⅰ超短超强脉冲激光装置。两次“突破”,不但有力地支撑了中国激光聚变与相关基础科学研究的高速发展,同时实现了中国高功率固体激光技术发展由“望尘莫及”到“望其项背”的跨越,奠定了由“望其项背”到与美、法先进国家“三足鼎立”的坚实基础。     

乳化液喷雾与微爆现象的激光全息实验研究

本文采用离轴高速多脉冲红宝石激光全息摄影仪研究高温高压环境中乳化液喷雾的雾化和蒸发过程,记录方式为象面全息方式,再现时分别采用激光和白光光源。实验发现:在适当的温度压力条件下,乳化液喷雾可以发生微爆现象,微爆呈团状,又称“团状微爆”,也称为“二次雾化”,微爆能量可以将众多的小液滴及液滴碎片抛出液束区,有效地改善液体与环境气体的混合过程,具有重要的理论意义和实用价值。     

Laser spectroscopic investigation of a new precursor-type polyparaphenylenevinylene

Optical, structural and morphological properties of thin films of polyparaphenylenevinylene (PPV) formed by an alkyl sulfinyl precursor route have been studied. Thin films were fabricated on an optical glass and on quartz glass either by spin-coating of the precursor solution or by layer-by-layer deposition using Langmuir–Blodgett technique. PPV precursor films were also spin-coated on gold-coated glass in order to study thin-film optical parameters by surface plasmon spectroscopy. We have been successful in forming about 40 precursor mono layers on quartz glass by Langmuir–Blodgett technique using optimized surface pressure and dipping conditions. After thermal conversion of the precursor layers good quality fluorescent PPV films of yellow colour have been obtained. Optical characterization of the films was carried out by linear absorption and emission spectroscopy, ellipsometry, and surface plasmon spectroscopy. Structural and morphological studies on the thin films were carried out by using X-ray scattering and atomic force microscopy. Wave-guided travelling-wave laser action has been achieved in a PPV film on quartz glass. The sample was transversally pumped with picosecond laser pulses (wavelength 347.15 nm, duration 35 ps). Laser emission occurred at 550 nm for pump pulse energy densities above .     

固体材料激光冷却的实验研究及其最新进展

近年来，基于反斯托克斯荧光制冷(Anti—Stokes Fluorescent Cooling)的固体材料激光冷却技术得到了快速发展。本文首先简单介绍了固体材料激光冷却的基本原理及其技术；其次，详细介绍了各种固体激光冷却的新材料、新方案和新结果及其最新实验进展；最后，就固体激光冷却技术的应用前景及其未来发展方向等问题进行了简单讨论与展望。     

343 nm飞秒激光制备微孔阵列以增强聚氨酯合成革透湿性

为了提高聚氨酯(PU)合成革透湿性,分别使用343 nm飞秒激光和作为对比的1030 nm飞秒激光及1064 nm纳秒激光制备微孔阵列。采用扫描电镜(SEM)和3D激光扫描显微镜对比研究了微孔形貌。结果表明,343 nm飞秒激光可以制备出效果最佳的微孔。此外,分析了3种激光与PU涂层的作用机理,揭示了343 nm飞秒激光合成革微钻孔过程仅表现为光化学烧蚀,光化学和光热烧蚀同时发生于1030 nm飞秒激光钻孔过程,而1064 nm纳秒激光只显示了光热烧蚀。激光合成革表面钻孔后,测量其透湿性和抗张力。结果显示: 微孔密度越大,皮革透湿性(WVP)越大而抗张力越低,脉冲重叠的增加会导致WVP的增加和抗张力的下降;同时,随着脉冲重叠从91.7%降到50%,微孔直径从45 μm降低到30 μm,而微孔锥度从0.7°增加到12.1°;当脉冲重叠率为91.7%,微孔密度为2550/cm²时,最大的WVP增长率为306%。     

Research on speckle noise of laser Doppler velocimeter for the vehicle self-contained navigation

A novel multipoint layer-type laser Doppler velocimeter (MLLDV) is designed to measure the velocity of a vehicle for the self-contained navigation system. In order to investigate the speckle's influence on the Doppler spectrum, formulas of time-lagged covariance and speckle broadening were derived for our MLLDV. Simulations and experiments are made for detailed analysis. The results show that the time-lagged covariance of photocurrent is directly proportional to the incident angle, and is inversely proportional to the elevation fluctuation of the ground together with the velocity of the vehicle. Speckle broadening is a function of the vehicle's velocity, the 1/e² Gaussian spot radius and the phase correlation length of the ground. For our MLLDV, Doppler frequency and Doppler broadening are both directly proportional to the velocity of the vehicle. Besides, the ratio between Doppler broadening and the corresponding Doppler frequency is about 0.72% when the speed of the vehicle varies from 0 to 9.6 m/s.