Tm3+掺杂的MFT玻璃蓝色荧光动力学

测量了Tm^3 掺杂的MFT玻璃材料的吸收光谱，J－O计算给出了该材料的光学跃迁强度参数Ωt(t=2,4,6)。测量了355nm激发下该材料的发射光谱，通过测量不同掺杂浓度Tm^3 的^1D2→^3H4和^1G4→^3H6荧光衰减曲线讨论了这两个能级寿命及荧光量子效随浓度的变化关系，计算当Tm^3 浓度的4％时引起^1D2和^1G4荧光猝灭的能量传递效率。指出了^1D2→^3H4的荧光猝灭属于电偶极－电偶极相互作用的能量传递所导致。     

掺铒铋酸盐玻璃光谱性质的组分依赖性研究

通过测试掺铒铋酸盐玻璃43Bi2O3-xB2O3-（57-x）SiO2（x=10，20，30，40，50mol％）中Er^3＋离子的吸收光谱、荧光光谱、荧光寿命及荧光强度，结合Judd—Ofelt和McCumber理论，对玻璃中Er^3＋离子光谱性质随玻璃组分的依赖关系进行了系统研究．研究结果显示，掺铒铋酸盐玻璃具有较其它玻璃优异的光谱性质．随着玻璃中组分B2O3含量的增加，强度参量Ω6、荧光半高宽和能级^4I15／2→^4I13/2间自发辐射跃迁几率相应增加，而荧光寿命、荧光强度和受激发射峰值截面相应减小，带宽品质因子（σe^pcak×FWHM）在组分B2O3含量30mol％时达到最大．     

掺铒铝硅酸盐玻璃光谱和上转换荧光性质研究

利用Judd小Ofelt(J—O)理论和吸收光谱计算了Er^3 、Yb^3 掺杂的铝硅酸盐玻璃的J—O参量、振子强度、跃迁几率、荧光寿命，量子效率以及上转换系数等参量，比较了饵离子^I13/2—^I15／2跃迁的光谱参量的计算与测量值，并讨论了玻璃中OH—浓度与荧光寿命、绿色上转换发光强度与抽运光功率的关系。     

Er玻璃近红外区上转换发光的研究

研究了Er,Yb共掺磷酸盐玻璃的上转换发光，对于在800nm附近的近红外发光进行了分析，认为该发光带是由于三种跃迁引起的，除了常见的4F9/2→^4I15/2跃迁以外，还存在着2H11/2→413/2,4S3/2→4I13/2的跃迁，还研究了Er^3 掺杂浓度对这三种跃迁的影响。     

硼碲酸盐玻璃材料中Er3+光谱性质对组分的依赖关系

采用熔融淬火技术制备了一组Er3+掺杂的变组分硼碲酸盐玻璃材料.测量了玻璃的折射率、吸收光谱及4I13/2→4I15/2跃迁的荧光寿命.利用标准的三参量Judd Ofelt理论对Er3+的光学跃迁性质进行了计算,并对Er3+离子的4I13/2能级的量子效率进行了研究.结果发现,随着样品中TeO2含量的增加样品的折射率变大,三个Judd Ofelt参量中Ω2随着样品组分的改变较明显,而另外两个参量Ω4和Ω6的变化较小.还发现随着TeO2含量的增加4I13/2→4I15/2辐射跃迁几率增大,并且该跃迁的量子效率增加.这一研究结果表明,在硼酸盐玻璃材料中引入TeO2可以有效地改善其中稀土离子的量子效率和辐射跃迁性能.     

铒离子浓度对掺Er3+碲酸盐玻璃的Judd-Ofelt理论参数的影响

制备了四种不同铒离子掺杂浓度的碲酸盐玻璃,通过测定吸收光谱计算了吸收谱线的振子强度,根据Judd-Ofelt理论计算了不同浓度下Er3 离子发光光谱的强度参数Ωi(i=2,4,6),计算了自发辐射电偶和磁偶跃迁概率、辐射寿命、荧光分支比等参数,讨论了Er3 离子浓度变化对以上这些参数的影响.测试了Er3 :4I13/2→4I15/2跃迁对应的荧光光谱和Er3 :4I13/2能级荧光寿命.最后应用McCumber理论计算了玻璃中Er3 :4I13/2→415/2跃迁对应的受激发射截面大小.结果表明:振子强度基本上随Er3 离子浓度的增大而增强;随着Er3 离子浓度的增加,自发辐射跃迁概率A基本呈现出递增的趋势,但荧光分支比β却只有很小的变化;Er3 :4I13/2→4I15/2的发射截面随Er3 离子浓度的增大而改变很小,有效线宽都在50 nm左右.     

Er3+/Yb3+共掺LiNbO3晶体中Er3+的光谱特性分析

在室温下,测量了采用Czochralski方法生长的as-grown和经退火处理的Z切Er^3＋／Yb^3＋共掺同成分LiNbO3晶体的α偏振吸收光谱（300-1650nm）。运用Judd—Ofelt理论对该晶体中Er^3＋的光谱特性进行了分析。由所测得的吸收系数的积分计算得到了从基态到激发态的若干个主要的电子跃迁强度实验值。利用最小二乘法确定出Er^3＋／Yb^3＋共掺LiNbO3晶体中Er^3＋的Judd-Ofelt参数。进而确定了自发辐射概率,从激发态能级到其各个下能级的荧光分支比以及能级辐射寿命。此外,还讨论了Yb^3＋的共掺和退火处理对LiNbO3晶体中Er^3＋光谱特性的影响。     

Cd3Al2SiO12玻璃中Er^3＋的光学跃迁

根据Judd-Ofelt理论,利用镉铝硅酸盐玻璃中Er^3 的吸收光谱,计算了实验与理论振子强度,用量小二乘法拟合实验与理论振子强度得到了三个J－O强度参数Ω2,Ω4,Ω6。并由此计算了Er^3 在不同能级之间的自发辐射系数A、辐射寿命τ、荧光分支比β以及积分发射截面∑。根据这些参数分析认为掺铒镉铝硅酸盐玻璃可能实现近红外激光输出。     

Er3+单掺和Er3+/Yb3+双掺铋硼酸盐玻璃的研究

用高温熔融法制备了Er^3 单掺和Er^3 /Yb^3 双掺铋硼酸盐玻璃样品，测量了上述玻璃样品的吸收光谱，荧光光谱，荧光寿命以及红外透过率。对高浓度掺杂Er^3 的铋硼酸盐玻璃中的浓度猝灭现象作出了解释。分析了Er^3 ／Yb^3 双掺铋硼酸盐玻璃样品中Yb^3 离子对Er^3 离子的敏化过程。研究发现Er^3 ／Yb^3 双掺铋硼酸盐玻璃在1．5～1．6μm波段有宽达81nm的荧光半峰全宽。实验还发现在熔制过程中通入氧气对其荧光寿命和红外透过率都有明显的提高。由于该玻璃材料表现出较好的物化性能。因此该材料可望成为宽带光纤放大器的适宜的基质材料。     

离子交换铒掺杂硅酸盐玻璃波导光放大特性

将集成光学放大器用于光纤通信系统中是人们越来越感兴趣的课题，由此导致人们寻找与此相适应的稀土掺杂玻璃材料。给出了一系列Er^3 ／Yb^3 共掺杂硅酸盐玻璃波导的制备和光谱特性的基本结果。平面和条型波导均由Ag^ -Na^ 离子交换技术制备。光谱测量显示，所有样品在1532nm都观测到了荧光发射峰．其半高谱宽为19nm。用波长为514．5nm和980nm的激光抽运，测得多数样品中Er^3 离子在亚稳态^4I13.2能级上的荧光寿命均为7ms左右。Er^3 ／Yb^3 共掺杂玻璃的上转换均低于单掺Er^3 玻璃。用250mW，波长为980nm的激光抽运3．5cm长的条形波导，在1536nm波段下得到的最大净增益是5dB，增益谱的半峰全宽是14nm。     

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.     

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.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.