偶氮材料中双波长共存的图象研究

测量了偶氮材料MO/PVA和EO/PVA的光致双折射,其值约为δ_n=2.7×10^-3.在同偏振态两路简并四波混频光同时作用于样品同一区域的条件下,研究了该材料的双波长共存特性,记录了光点存储和图象存储,并分析了双波长共存的竞争机制.     

PAR分光光度法测定钴和镍

进行了用PAR分光光度法同时测定钴和镍的研究。在pH=5的NaAc-HAc缓冲溶液中,钴和镍可与显色剂4-(2-吡啶偶氮)间苯二酚(PAR)的溶液形成稳定的络合物,络合物的吸收光谱重叠相互干扰,经过实验确定以508.0、568.0nm作为钴(Ⅱ)、镍(Ⅱ)的测量波长,应用双波长线性回归法可同时测定。方法简单、快速、灵敏度高。     

双色俘精酸酐薄膜的双波长图像光存储

采用两种光致变色俘精酸酐体系化合物[1,2,4-三甲基-5-苯基-3-吡咯甲叉(异丙叉)俘精酸酐和对-N,N-二甲基苯基-2-甲基-3-恶唑甲叉(异丙叉)俘精酸酐]制备了单层双色聚甲基丙烯酸甲酯(PMMA)复合薄膜感光记录材料。采用双波长(650nm和488nm)图像存储和读出光路,实现了用两种波长在双色复合薄膜的同一位置同时记录两幅图像。当分别用各自对应的波长读出时,两幅图像各自获得了高衬比度,且二者之间的串扰很小,证明了在双色光致变色俘精酸酐材料上进行双波长复用图像光存储的可行性。     

双波长全息术实验研究及在自适应光学中的应用

在双波长全息术中,全息图可用一个波长记录,用另一个波长重现。用光学寻址液晶空间光调制器作为记录介质,可方便实现动态双波长全息图的记录。经一个畸变波前记录动态全息图后,由具有相同畸变的另一个波前去重现该动态全息图,可以实现对光学波前畸变的等比例缩小。在用于自适应光学的负性反馈回路中时,可简化大波前畸变的测量过程,可在中红外光谱范围内记录并制作动态全息图畸变校正器(在此波段直接的全息记录是极难的),也能增大可校正的畸变范围。介绍了这种动态干涉仪的实验实现,及该动态全息记录技术应用于自适应光学的前景。     

LiNbO_3:In:Fe:Cu晶体中的双波长非易失存储

为了提高晶体的非易失存储性能,采用双波长存储技术实验研究了LiNbO3:In:Fe:Cu晶体中的非易失存储,折射率调制度为1.04×10-4,记录灵敏度达到0.965 cm/J.与传统的双色非易失记录相比,该方法大幅度地提高了光栅的强度和记录的灵敏度.利用Kukhtarev带输运模型对双波长非易失记录过程中光栅的动态演化过程进行了数值模拟,同时讨论了氧化还原程度对双波长非易失全息记录的影响.理论与实验符合的较好.     

推拉型偶氮化合物的三阶非线性和光学双稳效应

本文报道从推拉型偶氮化合物中测得了非常高的三阶非线性极化率,X~(3)～6×10~(→3)esu.这对于引起光学双稳现象是至关重要的.利用波长为488nm的氩离子激光为光源,从这类材料掺杂的玻璃态聚合物薄膜的Kretschmann型态中,进一步观察到了光学双稳现象.与此同时,联系这类材料的顺反异构化反应历程,从电子吸收机制或光诱导的折射率变化机制对有关问题进行了讨论.     

有机材料的多波长共线存储研究

以全波段共线输出四个波长的Ar离子激光器作为光源,采用简并四波混频（DFWM）光路装置,对一种新合成的偶氮材料样品作了多波开共线读出存储特性研究。实现了此类有机材料的实时和永久共线读出的存储,获得了良好的照片记录。实现了多波长读出双重存储,观测到并理论解释了多重存储、多波长存储之间的竞争现象。     

双波长数字全息相位解包裹方法研究

使用两个不同的波长分别记录数字全息图,分别由数值再现得到每个波长对应的包裹相位图,再求得两者的相位差得到等效波长的相位图,通过此双波长相位解包裹方法得到连续的相位分布以消除相位包裹。通过数值模拟研究了双波长相位解包裹方法,搭建了双波长数字全息实验系统,并利用660nm和671nm两个波长的激光对标准石英平片和平凹透镜进行了相衬成像。通过双波长相位解包裹方法得到了连续的相位分布,实验结果与数值模拟结果具有较好的一致性,证明了双波长相位解包裹方法的有效性。     

低T_g双功能型光折变聚合物的合成及其光致发光特性

以不同比例的重氮盐分别与聚双(N-羟基己氧基咔唑)磷腈(P-1)进行偶合反应,得到了一组以咔唑和对硝基偶氮咔唑为官能团的双功能型光折变聚合物P-2,P-3和P-4,用31 P NMR,1 H NMR,IR,TG,DSC和UV-Vis光谱对该组聚合物进行表征和分析,以325nm的激发波长对P-1,P-2,P-3和P-4进行固体荧光稳态发射光谱的测试。结果表明,该组聚合物具有良好的热稳定性(Td≈300℃)和较低的玻璃化温度(Tg≈30～40℃),P-1具有良好的荧光活性,硝基的引入,导致P-2,P-3和P-4的荧光发生不同程度的猝灭,咔唑与对硝基偶氮咔唑的数量及其空间分布排列的都会对其荧光性能产生影响。     

贝塔修正光度法分析微量金属配合物溶液性质研究:铅(Ⅱ)-二溴邻羧基偶氮氯膦多配位显色体系

本文采用双波长β修正光度法研究铅(Ⅱ)-二溴邻羧基偶氮氯膦(DBOK-CPA)多配位显色体系,在碱性条件下所生成络合物的组成比Pb2+∶DBOK-CPA为1∶7.配合物的各级真实吸光系数和稳定常数均被测得,在630nm处,络合物真实摩尔吸光系数ε=1.10×104L.mol-1.cm-1,络合物累积稳定常数K=3.04×1034(15℃和离子强度0.1).     

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.     

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.     

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.     

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.     

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.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.