k玻色子q相干态的反聚束效应

研究了q变形湮没算符高次幂(akq,k≥3)本征态的反聚束效应,并就k=3的情况用数值计算方法研究了q变形参数对该效应的影响.结果表明,当q变形相干态中谐振子的强度x=|z|2在某些区间内取值时,akq的本征态将呈现反聚束效应,并且这一效应明显地受到q参数的影响.当参数q取定时,随着q变形光场强度的变大,该光场的光子数涨落在经典(或量子)和量子(或经典)特性之间交替地变化.     

κ玻色子q相干态的反聚束效应

研究了q变形湮没算符高次幂（αq^k,κ≥3)本征态的反聚束效应，并就κ=3的情况用数值计算方法研究了q变形参数对该效应的影响。结果表明，当q变形相干态中谐振子的强度x=|z|^2在某些区间内取值时，αq^k的本征态将呈现反聚束效应，并且这一效应明显地受到q参数的影响。当参数q取定时，随着q变形光场强度的变大，该光场的光子数涨落在经典（或量子）和量子（或经典）特性之间交替地变化。     

q变形非简谐振子奇偶广义相干态的高阶压缩效应及反聚束效应

研究了q变形非简谐振子奇偶广义相干态的高阶压缩效应和反聚束效应,并就q变量[χ]的两种不同表示情况进行了讨论.数值计算结果表明,q变形非简谐振子奇偶广义相干态均可呈现奇次方阶压缩效应和反聚束效应,这与谐振子情况的光学统计特性是不同的.     

q变形非简谐振子湮没算符高次幂本征态的反聚束特性

研究了q变形非简谐振子湮没算符高次幂本征态的反聚束特性,并用数值计算方法定量研究了变形参量q对这一特性的影响.结果表明,q变形非简谐振子湮没算符高次幂本征态在非谐振子强度x│=β│²的若干取值区间内可多次交替地呈现反聚束效应,并且变形参量q对这一效应有很大的影响.     

减少光子奇(偶)对相干态的非经典特性

构造了减少光子奇对相干态与减少光子偶对相干态,并用数值模拟方法研究了它们的非经典特性。结果表明,从奇对相干态与偶对相干态的第一个场模取走光子,可以显著地增强第二个场模的光子统计亚泊松分布特性;从奇对相干态的第一个场模取走光子后,在双模光子消灭算符本征值的模较小时可以增强第一个场模的光子反聚束性质。从偶对相干态的第一个场模取走光子,在双模光子消灭算符本征值的模较小时第二个场模的光子反聚束效应得到明显增强。     

扩散过程中弱相干光场的退相干

研究了扩散过程中弱相干光场量子特性的演化.利用正规乘积、反正规乘积和Weyl编序算符内的积分技术,采用热纠缠态表象求解密度矩阵主方程,利用Kraus算符给出扩散过程中密度算符解的表达式,导出初态为弱相干态的量子态密度算符演化规律.讨论了扩散对光场压缩效应和反聚束效应的影响.结果表明:随着扩散过程的进行,弱相干场压缩深度和压缩范围均在减小;扩散初期光场呈反聚束效应,扩散时间大于一定值后反聚束效应消失.     

Q变形非简谐振子湮没算符高次幂本征态的反聚束效应

引入了一种量子反聚束效应,研究了Q变形非简谐振子湮没算符K次幂(K≥3)的K个本征态的量子反聚束效应,探讨了这些本征态的物理意义.结果表明,这K个本征态均可呈现量子反聚束效应,它们都可由不同时刻依赖于时间的Q变形非简谐振子广义相干态的线性叠加而生成.     

与q形变玻色算符逆算符相关的相干态及其量子统计性质

讨论了ｑ形变玻色算符的广义逆算符作用于ｑ－相干态所得到的两类量子态的数学及量子统计性质。结果表明，ｑ－相干态的光子激发态不存在压缩但呈现反聚束效应，而ｑ－相干态的光子湮灭态却存在压缩但不呈现反聚束效应。     

拉盖尔多项式算符激发相干态的非经典性质

将拉盖尔多项式算符作用在相干态上,构造了拉盖尔多项式算符激发相干态.利用有序算符积分技术,导出了它的归一化系数以及〈a^la^+m〉的计算表达式.采用数值计算方法,讨论了相干态相位角和平均光子数对它的非经典性质的影响.研究结果表明:一阶拉盖尔多项式算符激发相干态呈现出压缩效应、反聚束效应、亚泊松分布和Wigner函数负性等量子特性,并且相干态的相位角对它的量子特性有重要影响;另一方面,随相干态平均光子数增大,它的反聚束效应和亚泊松分布性质逐渐减弱,压缩效应和Wigner函数的负性却先增强,而后又逐渐减弱.     

激发双参数变形奇偶相干态的反聚束效应

通过在双参数变形奇偶qs相干态上重复作用玻色产生算符,构造了激发奇qs相干态aqs+m|α〉qso和激发偶qs相干态aqs+m|α〉qse,并用数值计算研究了参数m,s和q对反聚束效应的影响.结果显示:(1)当r较小时,对于偶qs相干态,激发可使原来强烈的聚束效应变为强烈的反聚束效应;(2)当q(q≤1)偏离1较远时,随着r2的增大,二阶qs相关函数出现振荡现象(即反聚束效应和聚束效应交替出现),其振幅和周期都随s和q的减小而增大,但不明显受m的调节;(3)当q→1时,二阶相关函数同样出现振荡现象,其振幅和周期不但随着s的减小而增大,而且明显地受到参数m的调节;(4)对于大多数r,二阶qs相关函数对s的敏感度大于对q的敏感度.     

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.