飞秒激光湿法刻蚀微纳制造

飞秒激光微加工作为一种新型微纳制造技术,在复杂三维构型制作方面具有其独特的优势,但激光加工效率问题严重制约了飞秒激光微加工技术走向实际工程应用,提出一种飞秒激光湿法刻蚀微纳制造方法,以提高飞秒激光微加工的效率为突破口,通过调控激光与物质相互作用获得材料的目标靶向改性,进而结合化学湿法刻蚀实现硬质材料上的高效和高精度三维微加工,采用这一方法制作出的微透镜尺寸为80 m,球冠高6.7 m,表面粗糙度小于10 nm。利用这种方法,实现了不同结构与特性的高质量微透镜阵列的超精密制备,在石英内部也实现了螺旋微通道的复杂三维结构,螺旋通道直径为20 m,长径比超过100。     

激光全息光刻技术在微纳光子结构制备中的应用进展

微纳光子结构研究随着光子学、半导体物理学及微加工技术的发展而逐渐蓬勃开展,并在其结构、理论、制备技术等方面取得了系列进展。受限于目前的微加工技术水平,要成功制备大尺度、高质量的光子材料仍然存在着一定挑战。激光全息光刻技术作为一种简便快捷的微结构制作技术已经发展成为一种经济快速制作大面积微纳超材料及光子晶体模板的重要手段。介绍了激光全息光刻技术的原理,详细阐述了该技术在制作三维面心立方、木堆积结构、金刚石结构光子晶体以及光学周期类准晶、手性超材料、周期性缺陷结构等微纳光子结构中的应用研究进展。激光全息光刻技术成功制作微纳光子结构为光子材料在更多领域的广泛应用提供了基础和方法。     

飞秒激光和酸刻蚀方法制作凹面微透镜阵列

基于飞秒激光光刻技术和氢氟酸对光学玻璃的刻蚀,在K9光学玻璃表面制作了凹面微透镜阵列,并且可以以此为模板实现凸微透镜阵列的大量复制.用相位对比显微镜和扫描电子显微镜分析了微透镜阵列的表面轮廓,测试了微透镜阵列的光学衍射特征.该方法简单、透镜参量可控,制作的微透镜阵列能够用于分光、光束匀化、并行光刻等强激光领域.     

飞秒激光和酸刻蚀方法制作凹面微透镜阵列

基于飞秒激光光刻技术和氢氟酸对光学玻璃的刻蚀,在K9光学玻璃表面制作了凹面微透镜阵列,并且可以以此为模板实现凸微透镜阵列的大量复制.用相位对比显微镜和扫描电子显微镜分析了微透镜阵列的表面轮廓,测试了微透镜阵列的光学衍射特征.该方法简单、透镜参量可控,制作的微透镜阵列能够用于分光、光束匀化、并行光刻等强激光领域.     

飞秒激光精密微纳加工的研究进展

飞秒激光由于其超快时间特性和超高峰值功率特性在精密微纳加工领域引起了人们广泛的重视．在与物质的相互作用中它能快速、准确地将能量作用在特定的区域内，从而可以获得极高的分辨率和加工精度。文章综述了飞秒激光精密微纳加工的最新研究进展，分别就飞秒激光烧蚀微加工和飞秒激光双光子聚合产生三维微纳结构进行了介绍，阐述了各自的物理机制．最后对飞秒激光微纳加工的研究前景做了初步探讨。     

利用飞秒激光直写实现透明介电材料中三维维微微纳结构的制备与集成

本文综述了利用飞秒激光三维直写技术,在玻璃和晶体等透明介电材料中实现微流体、微光学、微电子学等一系列功能性微纳结构,并进一步构筑新型微纳光子器件的原理、技术与应用。     

离子束刻蚀辅助飞秒激光加工制备碳化硅微光学元件

为了解决飞秒激光加工硬质材料所带来的表面质量差的问题,提出了离子束刻蚀与飞秒激光复合加工技术.利用飞秒激光加工技术在碳化硅表面制备微纳结构图形,然后通过离子束刻蚀技术对碳化硅微纳结构进行刻蚀,以调控结构的线宽和深度,使结构表面粗糙度由约106nm降低到11.8nm.研究表明,利用该技术制备的碳化硅菲涅尔波带片展现出良好的聚焦和成像效果.     

用飞秒激光脉冲在PMMA内页面式写入三维光存储的研究

用微透镜阵列聚焦放大的钛宝石飞秒激光脉冲到PMMA内部，在每个微透镜的焦点处造成光学损伤，通过改变焦点的位置，实现了三维数据的写入，用800 μJ 1 kHz重复率的飞秒激光记录速度达到20Mbit/s.阐述了数据信息的调制、写入和读出，分析了微透镜阵列参数对存储密度、数据记录速度和能量阈值的影响，建议了提高存储密度的两种有效途径. 关键词： 三维光存储 微透镜阵列 飞秒激光 PMMA     

多光束纳秒紫外激光制作硅表面微结构

使用波长351 nm的半导体泵浦全固态脉冲激光器作为光源,经过位相光栅分束,形成干涉光场,在硅表面直接刻蚀微结构,制作了周期为0.55 μm,槽深可达55 nm的一维微光栅和周期为1.25 μm,刻蚀深度45 nm的正交微光栅结构.给出了微光栅形貌结构的扫描电子显微镜和原子力显微镜的测量结果.正交微光栅的一级衍射效率在1.8%～6.3%之间.该研究是改变硅表面微结构,优化硅材料特性的一种新方法,并扩展了大功率激光刻蚀在表面微加工领域的应用.     

单晶金刚石微杯形谐振子的激光刻蚀制造方法

基于激光刻蚀技术,提出了一种新型单晶金刚石微杯形谐振子的三维制造方法。由于高弹性模量、低热弹性阻尼以及较大的声波传递速度等优异的性质,单晶金刚石是一种理想的谐振子加工材料,但是金刚石硬度大且化学性能稳定,难以采用传统的加工方法成形加工。激光刻蚀因精度高,加工结构对称性好以及破损率低等特点,是一种较好的单晶金刚石加工方法。采用紫外激光加工机,研究了不同激光参数对单晶金刚石刻蚀质量的影响,通过合理设计微杯形谐振结构,规划激光刻蚀加工的轨迹,采用优化后激光刻蚀参数,实现了结构对称性较好的微杯形谐振子的加工,有望应用于高性能微杯形谐振陀螺。     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.