LiNbO3波导中切伦科夫辐射型的倍频

对条波导中切伦科夫辐射型的倍频作了简要分析，着重分析了产生切伦科夫辐射倍频的，工从实验上实现了条波导中１．０６μｍ红外光到０．５３１ｍ绿光的倍频辐射，转换效率为的０．９％，对应的输入光功率为１０ｍＷ。     

Cherenkov Radiation Generated by an Electron Bunch in a Rectangular Dielectric Waveguide Filled with a Transversely Isotropic Medium

Technical Physics - Dielectric waveguides are being intensively studied as accelerating structures excited by an electron bunch. Rectangular dielectric structures are used both to test the...     

Features of the Sound Field Structure in a Two-Channel Oceanic Waveguide

The results of experimental studies of the energy and angular structure of a sound field in the region of the Iberian Basin in the northeastern Atlantic are discussed. The experiments are carried out in a two-channel waveguide whose axes are located at depths of approximately 450 and 2000 m. A continuous pseudonoise signal in the frequency range 2.52–4.0 kHz is emitted. The signals are received by the omnidirectional hydrophones and, simultaneously, by a 10-m-long vertical array, which allows one to realize a narrow beam reception (～2.5°) in the vertical plane. The source and the receiver are located in a 500-m-thick layer within the upper sound channel. The field characteristics are measured in the course of a continuous change of distance from 1 to 65 km. The comparison of the experimental data with calculations shows that the sound field structure formed by the lower channel is much closer to the theoretical results than the structure formed by the upper channel. In the upper sound channel, the shadow zone manifests itself only slightly and the first convergence zone begins approximately 72–11 km nearer to the source than predicted by the calculations. The corresponding angular sound field structure is fairly pronounced in the vertical plane and bears no evidence of the random behavior that is peculiar to the fields scattered by the inhomogeneities.     

传输损耗对条形波导中切伦科夫倍频的影响

基于耦合模理论,分析了考虑传输损耗的条皮导中切伦科夫（Cherenkov)二次谐波（SHG）的问题。结果表明,转换效率具有指数性质和饱和性质。这一结果不同于未考虑传输损耗时转换效率所具有的线性性质,这对于切伦科夫频率倍频器的研制中参数的优化具有重要的意义。     

Cherenkov Radiation in Moving Medium

Cherenkov radiation in uniformly moving homogeneous isotropic medium without dispersion is studied. Formula for the spectrum of Cherenkov radiation of fermion was derived for the case when the speed of the medium is less than the speed of light in this medium at rest. The properties of Cherenkov spectrum are investigated.     

Synchrotron Radiation in a Circular Metallic Waveguide

We study theoretically the influence of a circular metallic waveguide with a longitudinal magnetic field on the synchrotron radiation of a point electric charge moving along a helical trajectory coaxial with the waveguide axis. The main attention is focused on the analysis of the energy characteristics of radiation of electromagnetic E and H waves. We derive the formulas for the radiation powers of E and H waves. It is shown that, under certain conditions, slowly moving electric charges do not radiate any of these electromagnetic waves in the circular waveguide.     

Field Structure in the Cross Section of a Ferrite Inhomogeneous Anisotropic Insert of a Rectangular Waveguide

We develop a physico-mathematical model describing excitation and distribution of electromagnetic waves in an anisotropic waveguide or resonator in the three-dimensional case. We develop a theoretical approach for discretization of the Maxwell equations in an arbitrary medium in the presence of bounding walls of a waveguide or resonator. The resulting system of linear algebraic equations for the electric-field components in an inhomogeneous anisotropic medium is solved by the method of biconjugate gradient. The results of calculating the electric field lines in the cross section of an anisotropic insert of a rectangular waveguide are presented.     

Cherenkov Radiation Emission in uniaxial optical materials

We report a theoretical study of the Cherenkov radiation emission in uniaxial optical materials. The formalism is based on the previous work of Muzicar (1961) whose results in terms of energetic properties of the emitted waves are corrected. This formalism is used to predict the Cherenkov radiation emission in a strongly birefringent sodium nitrate crystal (NaNO₃). Received: 24 October 1997 / Accepted: 10 December 1997     

Peculiarities of Cherenkov and Transition Radiation in a Finite-Size Absorbing Medium

Russian Physics Journal - Based on the equations of macroscopic electrodynamics, the spectral-angular characteristics of electromagnetic radiation are considered, which is generated during the...     

Electric Field Analysis of Non－coplanar Electrodes in Electrooptic Modulator with a Ridge Waveguide Structure

ＥｌｅｃｔｒｉｃＦｉｅｌｄＡｎａｌｙｓｉｓｏｆＮｏｎ－ｃｏｐｌａｎａｒＥｌｅｃｔｒｏｄｅｓｉｎＥｌｅｃｔｒｏｏｐｔｉｃＭｏｄｕｌａｔｏｒｗｉｔｈａＲｉｄｇｅＷａｖｅｇｕｉｄｅＳｔｒｕｃｔｕｒｅ￥ＺＨＯＵＹｉ；ＹＵＹａｎｇ；ＱＩＵＷｅｉ；ＣＨＥＮＹｉｘ...     

Field theory of dielectric Cherenkov maser

The effect of three-dimensional perturbed velocity and three-dimensional perturbed current density on the beam-wave interaction of dielectric Cherenkov maser is analysed by use of the self-consistent linear field theory. Three distinct cases are considered. First, the propagation of the electron beam in an annular dielectric liner enclosed by a loss-free conducting wall is investigated. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. It's clearly shown that the instability of the interaction results from the coupling of the TM mode in the dielectric lined slow-wave waveguide to the beam mode via the electron beam. And the coupling is proportional to the density of the beam. The growth rate of the wave produced by the electron beam are obtained. Then, the case of a relativistic electron beam guided by a longitudinal magnetic field in the same slow-wave structure is examined. The motion of electrons could be approximated to be one-dimensional when the simultaneous condition of the beam-wave interaction of dielectric Cherenkov maser is satisfied. Finally, the effect of the background plasma on the instability of the beam-wave interaction is studied.This work is supported by National Natural Science Foundation of China.     

An Experimental Study on Cyclotron–Cherenkov Radiation

We searched numerically dielectric-loaded cylindrical waveguide configurations with an injected electron beam in which the growth rate of the cyclotron-Cherenkov instability surpassed that of the Cherenkov instability, and found such a configuration. This configuration consists of a metallic core and an outer metallic cylinder with a dielectric liner on the inner surface. In order to investigate experimentally radiation due to the cyclotron-Cherenkov instability, we designed and assembled an experimental device using the computational results. We studied beam propagation in the dielectric-loaded coaxial waveguide and microwave radiation due to the cyclotron-Cherenkov instability and the Cherenkov instability.     

X-Ray Cherenkov Radiation in an Absorbing Medium with Finite Dimensions

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - The spectral-angular characteristics of the electromagnetic radiation produced during the propagation of fast charged...     

Diffraction Radiation from a Slot in the Impedance End of a Semi-Infinite Rectangular Waveguide

Using the induced magnetomotive force method, we obtain an approximate analytical solution of the problem of diffraction of the H₁₀ mode by a narrow slot which is cut in the impedance finite-thickness wall on the end of a semi-infinite rectangular waveguide and radiates into free half-space over an infinite, perfectly conducting screen. The scattering-matrix coefficients of a slotted waveguide radiator are studied numerically for the values of the complex surface impedance which correspond to some particular types of a thin-film coating of the waveguide end wall.     

Analysis of Radiation Phenomena in a Wedge Ended Dielectric Slab Waveguide

Radiation phenomena observed in a wedge shape ended dielectric slab waveguide are analyzed using mode matching technique. The case of transverse electric polarization (TE) being parallel to dielectric slab waveguide is assumed. In order to describe the fields in the wedge region, a stack of dielectric plates is assumed and in each layer the fields are expanded in terms of the mixed spectrum of guided and radiated modes. A similar expansion is used in the constant thickness slab waveguide while in free space medium a continuous-radiation mode expansion is used. Then a mode matching approach is applied, incorporating the orthogonality properties of mixed spectrum modes, in order to compute the wave fields inside the dielectric slab waveguide and wedge medium. Mode matching is achieved by discretizing the continuous radiation mode spectrum leading into a numerically stable solution provided a sufficient large number of points are used to convert integrals into finite summations. Numerical computations are carried out for various wedge geometries and shapes including linear and exponential profiles.     

Characteristic Thicknesses of a Four-Layer Waveguide Structure

Russian Physics Journal -     

Computation of Electric Field Components and Standing Wave Coefficient for a Waveguide Structure with a Lowohm Semiconductor Plate

The boundary problem for Maxwell equations has been solved and computer codes have been written to compute the electrodynamic characteristics of the waveguide structure. The standing wave coefficient's (SWC) dependence on sizes of a n-Si plate, displacement from the waveguide's symmetry plane and electric field amplitude's distribution in these plates have been computed.     

Study of the Effect of Pulsed-Periodic Electric Field and Linearly Polarized Laser Radiation on the Properties of Liquid-Crystal Waveguide

Integrated-optical waveguides with a nematic liquid-crystal 4-cyano-4’-pentylbiphenyl (5CB) waveguiding layer have been investigated for different polarizations of incident laser radiation and under a pulsed-periodic electric field. A dependence of the damping coefficient of waveguide modes and the sizes of quasi-steady-state irregularities of nematic liquid-crystal layer on the linear polarization of laser radiation and the strength of pulsed-periodic field has been found experimentally. The correlation length is estimated for waveguiding layer irregularities. The waveguide scattering method has provided a resolution in correlation length exceeding the classical resolution limit by approximately an order of magnitude. The observed decrease in the damping coefficient of waveguide modes and irregularity sizes under external field is explained by the decrease in the correlation length of director fluctuations.     

矩形波导中超短脉冲电子束的相干同步辐射

考虑了当射频调制的超短脉冲电子束径向长度远小于辐射波长时，将其理想化为δ时间函数，提出了用波导本往模展开的方法来计算矩形波导中超短脉冲电子束的相干同步辐射及其频率特性。结果表明：（１）当谐振频率等于调制电子束微脉冲时间隔的射频的整数倍时，辐射模式表现为“纯”的波导本征模。（２）波导效应使得超短脉冲电子束在两个频率处发生相干同步辐射，而且低频支的辐射功率高于高频支的。最后指出波导自由电子激光器单横模     

Diagnostics of Electron Beams Based on Cherenkov Radiation in an Optical Fiber

Russian Physics Journal - The use of an optical fiber in which Cherenkov radiation is generated instead of a metal wire for scanning a beam profile allows a compact and noise-proof device for...