渐变折射率波导传播特性微扰计算的代数递推公式

应用量子力学的超位力定理（HVT）和赫尔曼－费恩曼（Hellmann-Feynman）定理（HFT），导出了用微扰法计算渐变折射率平面波导传播常数各级近似值的代数递推公式，并给出了由传播常数近似值计算模场近似表达式的代数式。计算了几个典型实例，此法的特点是便于直接计算任意级近似的传播常数及模场分布，且可推广到二维波导的计算。     

Born近似散射幅的分波法推导

本文给出一种不同于通常教科书的推导散射振幅的Ｂｏｒｎ近似公式的方法．通过求解径向运动方程，我们得到了微扰的辏力场Ｕ（ｒ）产生的相移δｌ，再根据计算散射幅的分波法一般公式，并利用Ｇｅｇｅｎｂａｕｅｒ加法公式，推出了 Ｂｏｒｎ近似下的散射幅．     

GeSi合金1×4Y级联分束器的有限差分束传播法模拟设计

进一步研究二个问题：（１）理论模拟的方法由快速傅里叶束传播法（ＦＦＴ－ＢＰＭ）改为有限差分束传播法（ＦＤ－ＢＰＭ），并比较了两者的优缺点。（２）模拟设计了对象提高为由ＧｅＳｉ合金单模脊形光波导组成的Ｙ级联１×４光分束器。结果表明，有限差分束传播法比快速傅里叶束传播法及显形有限差分束传播法（ＥＦＤ－ＢＰＭ），除了数学比较容易外，计算速度也快一些。尤其是对传播步长Δｚ的敏感性，有限差分束传播法远没有快速傅里叶束传播法那样严重，便利了束传播法方法的采用。正如束传播法成功地应用于ＧｅＳｉ合金光波导及Ｙ分支器的理论设计，现在用了１×４Ｙ级联分束器同样得到预想的结果。光束在分束器中传播逐步分成二束再分为四束。符合设计要求。     

无简并微扰公式的递推形式在Lipkin模型中的应用

本文给出了量子体系无筒并态微扰公式的递推形式．在微扰计算收敛的情况下，利用它可以方便地计算任意级的微扰近似．列出了在Ｌｉｐｋｉｎ可解模型下的理论计算结果．     

Ab Initio/有限场方法计算尿素分子的非线性光学极化率

用有限场（ＦＦ）方法在４－３１Ｇ＋２ｐ２ｄ水平上研究了外加电场强度对尿素分子的偶极矩,极化率,一阶超极化率,二阶超极化率的影响。计算发现,要获得上述性质的稳定计算结果,电场强度需确定在０．００１－０．００４ａ．ｕ．范围内。在此电强度范围内,与耦合微扰Ｈａｒｔｒｅｅ－Ｆｏｒｋ（ＣＰＨＦ）法的计算结果符合较好,且可有效地利用二级微扰方法（ＭＰ２）进行电子相关计算。     

3d＿（z￣2）基态铜（Ⅱ）冠醚配合物的粉末ESR谱

制备了两种不同基质的掺杂３ｄ＿（ｚ￣２）基态铜（Ⅱ）苯并１５冠５配合物（Ｃｕ（Ⅱ）Ｂ１５Ｃ５）的粉末样品，ＥＳＲ测定结果表明，以Ｂ１５Ｃ５为基质时，Ｃｕ（Ⅱ）Ｂ１５Ｃ５的轴向配体是Ｈ＿２Ｏ；而以Ｍｇ（Ⅱ）Ｂ１５Ｃ５为基质时的轴向配体则是．不同的轴向配体对ＥＳＲ谱的线型有着较大的影响。利用Ｂｌｅａｎｅｙ公式，计算了键参数，并对成键特性进行了讨论和比较。     

环糊精—表面活性剂包结作用的研究

应用表面张力方法研究了β－环糊精（β－ＣＤ）对十二烷基苯磺酸钠（ＳＤＢＳ）的包结作用，研究了不同温度下β－ＣＤ对ＳＤＢＳ表面活性的影响以及脂肪醇加入β－ＣＤ包结ＳＤＢＳ表面活性的影响，求得了不同温度下β－ＣＤ包结ＳＤＢＳ的平衡常数Ｋ，并用＾１ＨＮＭＲ波谱探讨了包结物β－ＣＤ／ＳＤＢＳ的分子结构模型。     

无反射势阱的非齐次Schr(o)dinger方程的精确解

无反射势阱描述一种双原子分子的吸引势。将Ｒａｙｌｅｉｇｈ－Ｓｃｈｒｏｄｉｎｇｅｒ展开法应用到微扰无反射势阱,得以一组非齐次Ｓｃｈｒｏｄｉｎｇｅｒ方程。利用最近报道的微扰方法,导出这些方程的积分形式的精确解。以静电场与基态系统的相互作用为例,通过精确解的有界及其不能在Ｈｉｌｂｅｒｔ空间展开为有限项的性质,论证了该微扰系统束缚态的存在性及通常量子力学发散困难的起因。     

高T_c氧化物体系的相关系和晶体结构

本文综述了Ｒ－Ｂａ－Ｃｕ－Ｏ体系，Ｂｉ－Ｓｒ－Ｃａ－Ｃｕ－Ｏ体系，Ｔ１－Ｂａ－Ｃａ－Ｃｕ－Ｏ ＃系，Ｔ１－Ｓｒ－Ｃａ－Ｒ－Ｃｕ－Ｏ体系以及Ｐｂ－Ｓｒ－Ｒ（Ｃａ）Ｃｕ－Ｏ体系超导相的相关系和晶体结构，并讨论了超导相的结构特点和它们之间的相互关系．     

量子力学中的微扰变分法

本文介绍了量子力学中将微扰法和变分法结合起来考虑的微扰变分法，该方法可以同时兼有两种近似方法的优点．而且，由变分法求得的ψ－ｋ～（１）即可求能量二三级修正Ｅ－ｋ～（２）和Ｅ－ｋ～（３），由ψ－ｋ～（２）可求得四五级修正Ｅ－ｋ～（４）和Ｅ－ｋ～（５），如此等等．     

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.     

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.     

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.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.     

Direction-of-arrival estimation using matrix spatial prefiltering approach

An approach to direction-of-arrival （DOA） estimation for multiple narrowband farfield signals is proposed. The technique uses a novel matrix spatial prefiltering approach. Specifically, a matrix filter is designed to spatially filter the incoming data snapshots. The un-wanted components arriving from the stopband angular sectors are attenuated and the desired components from the angular sector of interest pass with minimal distortion. The matrix filter spatially filters the element-space data and the output reserves the element-space data property, which makes it very useful by passing sensor data through a spatial prefilter prior to applying many other array processors to attenuate interferences and improve system performance. Several examples of DOA estimation problem are presented to illustrate the performance of the proposed spatial prefiltering approach. Results of simulation and real data show that the pre-filter can efficiently attenuate the spatial interferences and significantly improve the estimation and resolution capability of DOA estimators at low signal-to-noise ratios for the sources located inside the passband sector. In addition, the use of spatial prefilter makes it possible to estimate DOAs for multiple sources more than the number of the elements of an array.     

Quantum efficiency calibration of opto-electronic detector by means of correlated photons method

A new calibration method of detectors can be realized by using correlated photons generated in spontaneous parametric down-conversion (SPDC) effect of nonlinear crystal.An absolute calibration system of detector quantum efficiency is performed.And its principle and experimental setup are introduced.A continuouswave (CW) ultraviolet (351 nm),diode-pumped,frequency-doubled,and solid-state laser is used to pump BBO crystal.The quantum efficiencies of the photomultiplier at 633,702,and 789 nm are measured respectively.The coincidence peaks are observed using coincidence circuit.Some measurement factors including the filter bandwidth of trigger channel,the detector position alignment and polarization of the pump light are analyzed.The uncertainties of this calibration method are also analyzed,and the relative uncertainties of total calibration are less than 5.8%.The accuracy of this method could be improved in the future.