磁光光纤中光脉冲的非线性传播特性研究

根据光纤中磁光效应与非线性效应的微扰理论,推导了磁光光纤中光脉冲的非线性耦合模方程,比较了修正的分步傅里叶算法中磁光效应的时域和频域处理方案,表明了在步长足够小的情况下,两种方案的结果一致.分析了磁光效应、光纤非线性以及色散对光脉冲传输特性的影响,通过改变磁光耦合强度,不但可以灵活控制脉冲形状,还可以改变非线性引起的频率啁啾大小,有助于实现基于光脉冲展宽的动态整形功能.本文给出的理论分析方法,有助于开发可用于光纤通信、光纤传感等领域的基于非线性磁光光纤的新型磁光信息处理器件.     

Extension of the generalized multipole technique to three-dimensional anisotropic scatterers

New expansions are derived for the simulation of three-dimensional anisotropic scatterers with the generalized multipole technique (GMT). This extension of the GMT makes possible the investigation of subtle phenomena such as the interaction of light with realistic crystals or magneto-optic materials.     

直接观测磁通密度分布和运动的磁光图像技术

阐述了应用法拉第磁光旋转效应将磁通密度分布转换为亮度分布的图像，介绍了用微机采集和处理这种磁光图像，直接观测和研究磁通密度分布和运动，研究超导体的磁通动力学和磁性材料的磁性结构，叙述了目前应用磁光图像技术研究高温超导体性质和实用高温超导带材方面的最新进展．     

磁光盘反射率测试方法研究

磁光盘反射率是一个重要的参数，在磁光盘的研制和生产过程中必须进行测试。本文首先介绍了反射率测试的典型方法，然后结合磁光盘磁光特性伺服测试系统提出了一种测试磁光盘反射率的实用有效的方法，使磁光盘磁光特性测试仪既能测试克尔角又能测试反射率。最后对该方法测试反射率的误差进行了评估，并给出了测试实例。     

Highly sensitive detection of biomolecules with the magneto-optic surface-plasmon-resonance sensor

The characteristics of a novel magneto-optic surface-plasmon-resonance (MOSPR) sensor and its use for the detection of biomolecules are presented. This physical transduction principle is based on the combination of the magneto-optic activity of magnetic materials and a surface-plasmon resonance of metallic layers. Such a combination can produce a sharp enhancement of the magneto-optic effects that strongly depends on the optical properties of the surrounding medium, allowing its use for biosensing applications. Experimental characterizations of the MOSPR sensor have shown an increase in the limit of detection by a factor of 3 in changes of refractive index and in the adsorption of biomolecules compared with standard sensors. Optimization of the metallic layers and the experimental setup could result in an improvement of the limit of detection by as much as 1 order of magnitude.     

磁光盘微光斑参数实时测量的频谱分析法

本文在频域对磁光读出过程进行了分析，提出了一种方便实时测量磁光存储系统中的微光斑参数的新方法－频谱分析法。误差分析表明，该方法精度高，易于实现。     

Scanning laser techniques for dynamic thermo-magnetic recording onto stationary media

Scanning laser microscopes (SLMs) have been used to characterise the magnetic properties of materials for some time (J. Magn. Magn. Mater. 95(1) (1991); IEEE Trans. Magn. 31(6 Pt. 1) (1995)). An SLM has been designed to facilitate a number of operating modes: both for writing and reading magneto-optical data. The current SLM is capable of thermo-magnetically recording bits onto magneto-optical thin films. Unlike previous SLMs, the current instrument has been designed to write bits both statically and dynamically onto stationary media. It will be used to write to magneto-optic (MO) disk material thermo-magnetically prior to imaging. Images may be derived from the longitudinal and polar magneto-optic Kerr effects, which are wavelength dependent, using the appropriate laser wavelength. In this paper the two configurations for dynamic recording are described.     

磁光非线性光纤中光参量增益的研究

将光纤中磁光效应和非线性效应作为微扰,推导了磁光四波混频的耦合模方程.通过解析解研究了各向同性磁光非线性光纤的参量过程,并指出利用磁光耦合系数的色散特性可以实现四波混频的相位匹配.同时,采用龙格-库塔法分析了在线双折射磁光非线性光纤中,忽略费尔德常量的波长依赖性时,左旋圆偏振光参量增益的磁控特性,指出了实验中采用较高费尔德常量的非线性光纤的必要性.研究表明:1)对于低线双折射磁光非线性光纤,优化双折射大小可以获得最大的参量增益;2)根据参量增益对磁光耦合系数的单调依赖特性,适当选择光纤长度、泵浦功率以及输入导波光的偏振态,可使参量增益的磁可调范围大大提高.     

Real time dynamic domain observation in bulk materials

The paper briefly reviews the development of domain observation techniques used to study basic properties of electrical steels. A new real-time, dynamic, high magnification domain observation technique is presented as an example of a state-of-the-art system, capable of imaging non-repetitive domain wall motion at power frequencies. Advantages of real-time domain observation over stroboscopic magneto-optic studies are presented and the need for real-time observations in developing future loss theories is proposed. Possible relationships between Barkhausen noise, hysteresis and non-repetitive wall motion in electrical steels are suggested and finally examples of non-repetitive wall motion in other magnetic materials are illustrated.     

高密度冷原子云辐射陷获效应造成的荧光减弱现象

实验测量了磁光阱的磁场关断之后的荧光变化,观察到几十ms量级的荧光上升过程. 根据实验条件进行分析,在高密度冷原子云中辐射陷获效应造成额外的非相干抽运光场是造成磁光陷阱紧束缚状态下荧光减弱的原因. 同时还进行了简单的数值模拟,结果表明只有考虑到散射光场的频率重分布效应,计算结果方能与实验符合. 关键词： 冷原子云 辐射陷获 频率重分布     

Optical methods for measurement of voltage and current on power systems

The basic principles of optical methods for measuring voltage and current at high voltage are presented. These include the magneto-optic effect, the electro-optic effect and the electrogyration effect, plus various detection and noise reduction techniques. Both free path and enclosed path devices which have been constructed on these principles are described. The viability of these devices for the electricity supply industry is assessed.     

Numerical display element exploiting “rag-domains” garnet films

Magnetic garnet films derived from bubble-films by lowering the magnetization have been recently illustrated and proposed as basic materials for a new type of magneto-optic display. In this paper the first operational numerical display element of this new kind is presented.     

Magneto-optics of antiferromagnets

Antiferromagnetic crystals in which crystallographic sites occupied by magnetic ions from various sublattices are not transnationally equivalent and are not associated with each other by a symmetry center can have magneto-optic properties distinct from the properties of other antiferromagnets. In particular, birefringence and dichroism of linear polarized light can be observed which are directly proportional to the magnetic field strength, as well as magnetic rotation and circular dichroism quadratic in the field strength. Both effect—the linear magneto-optic effect and quadratic magnetic gyration — are sensitive to the crystal magnetic symmetry and to reorientation of the antiferromagnetic vector. Both effects reverse their signs when the directions of the magnetic moments of a sublattice are changed. These properties of new magneto-optic effects can be used to study the time-reversed domain structure of antiferromagnets, to define the symmetry of magnetic ordering and to study the magnetic crystal energy spectra by spectroscopic methods. The results of experimental studies of the linear magneto-optic effect and quadratic magnetic rotation in tetragonal antiferromagnetic fluorides of transition metals, manganese-germanium garnet and other antiferromagnets are reported. Experimental results on the domain structure of high symmetric antiferromagnets, the point magnetic symmetry of non-collinear multisublattice antiferromagnetic garnet MnGeG are discussed.     

Magneto-optical ellipsometry

Through the extension of the Yeh's formalism (Surf. Sci.96 (1980) 41) to magnetic crystalline media the formulas of the magneto-optic ellipsometry and the dispersion relations for wave-guiding in multilayer magnetic crystalline structures are obtained. The theory covers most of the situations considered so far in the magneto-optics in which the optical response of the structures is linear in the amplitude of the incident wave. It is capable of treating the interfaces between two magnetic media and the structures containing such interfaces with no restrictions on the orientation of the magnetizations and crystalline axes at an arbitrary angle of incidence. The polar, longitudinal and transversal magnetizations in the structures are considered as special cases. Possible applications of the theory are in the analysis of the planar multilayer magneto-optic systems in the integrated optics and magneto-optic memory technology, in the study of profiles of magnetic surfaces subjected to mechanical wear, ion implantation, etc.     

Interference amplification of the magneto-optic Kerr effect in multilayer structures in the X-ray range

The problem of X-ray reflection from multilayer structures with magnetic layers has been solved. The matrix for reflection of electromagnetic waves from such structures has been calculated analytically in kinematical and dynamical approximations. It is shown that not only reflection coefficients, but also magneto-optic effects are enhanced near Bragg peak. The possibility of measuring magneto-optic effects in multilayer structures without using synchrotron radiation has been estimated.     

Bi4Ge3O12晶体的磁光法拉第旋转

在可见光范围测量了Bi₄Ge₃O₁₂晶体磁光法拉第旋转的色散关系,也测量了从室温到液氮温度磁光旋转在633nm的变化。大的磁光旋转和很宽光波范围的高透过率表明晶体在磁光应用上也是很有价值的。扼要讨论了Bi离子在抗磁晶体中对磁光旋转的重要作用。 关键词：     

Acoustic characteristics of composite materials as acoustic window at oblique incidence of sound waves

This paper described a method for estimating the acoustic characteristics of composite materials at oblique incidence of sound waves. Composite materials are used as acoustic windows of SONAR to protect the internal sensors and electronic parts from water. In this study the composite material of glass reinforced plastic and polyurethane was used as the specimen. As the acoustic characteristics the velocities and attenuation coefficients of sound waves through the composite material were measured in the high frequency range. The insertion loss was also measured as a function of incident angle at 200 and 76 kHz, respectively. The attenuation coefficients in the low frequency range were estimated by interpolating the measured attenuation in the high frequency range with power-law form fitting. A four-medium layer model was proposed to estimate the insertion loss of composite materials at oblique incidence of sound waves in the low frequency range. The four-medium layer model well described the experimentally measured insertion loss at the high frequency range. It suggests that the insertion loss of the composite materials can be well estimated as a function of incident angle in the low frequency range.     

Additivity of the Kerr effect in thin-film magnetic systems

A universal approach is developed for calculating magneto-optic coefficients in multimedia systems. Three configurations are described: (i) a two-media, one-boundary system, (ii) a film sandwiched between two media and (iii) a multilayer system, such as a superlattice or even a randomly stacked sequence. It is proven that in the thin-film limit, the Kerr effect for a multilayer system obeys an additivity law: it is equal to the algebraic sum of the Kerr signals of the individual magnetic films in the system. The prediction is verified experimentally and in numerical calculations on an Fe/Cu/Fe 3-layer stack grown on a Pd-substrate.     

高功率微波场磁光传感技术研究

 本文介绍一种利用磁光晶体记录特性进行高功率微波场矢量测量的传感技术。对返波管振荡器微波场的多点阵列测试表明,该传感系统对被测场无影响,抗干扰能力强,空间分辨率为0.001m,可测出场的主要模式成份TM₀₁、TE₀₁和TE₁₁,以及各成份的场强和功率,对总功率的估算值与喇叭耦合测量结果有较好的一致性。     

高功率隔离器热致退偏分析与补偿设计

针对磁光晶体在大功率光隔离器中的应用,结合实际光学元件参数,利用琼斯矩阵分析了隔离度与入射光功率间的关系。提出基于外置材料,对磁光晶体热致退偏效应的补偿方案:针对两种不同的常见补偿材料,给出了它们的设计参数,并对两种材料的补偿效果进行对比。结果表明,在50 W的光功率下,利用CaF2晶体和SiO2,可分别提高隔离度约15dB和4dB。