Two-dimensional analysis of a dielectric waveguide mirror

We present the two-dimensional (2-D) mode numerical analysis of a dielectric waveguide mirror with arbitrary structure angle. This work is an extension of a previously reported one-dimensional (1-D) mode analysis which accounts for the transverse variation, in addition to the lateral, of the waveguide modes. Inclusion of the transverse confinement is very important and has a significant effect on the predicted characteristics of the dielectric mirror. The dependence of the modal reflection on mode confinement and transverse and lateral mirror tilt is evaluated. In addition, the farfield is predicted and results in an unusual and unique crescent shaped distribution for angled incidence to the mirror. These mirrors are finding increasing use in many optical devices and systems including turning mirrors, lasers, and optical switches and couplers. With this expanding application, the characterization of these mirrors is paramount     

Experimental study of a quasi-optical cavity with slotted output mirror

This paper describes an experimental study of a quasi-optical cavity to be used in qyrotrons. The cavity configuration was designed so that its output wave could pass into a quasi-optical transmission line. The test cavity was coaxially composed of a pair of annular mirrors, one of which was a curved conical mirror and the other was a plane mirror having a radial slot array for wave output. A mode excited in the cavity at 56.4 GHz was observed by detecting the radiation wave that leaked out through the slotted mirror. It was shown that the present slotted mirror served as a partially and uniformly transparent mirror to radiate the output wave with the same mode as in the cavity.     

The resonant cylindrical dielectric cavity antenna

An experimental investigation of the radiation and circuit properties of a resonant cylindrical dielectric cavity antenna has been undertaken. The radiation patterns and input impedance have been measured for structures of various geometrical aspect ratios, dielectric constants, and sizes of coaxial feed probes. A simple theory utilizing the magnetic wall boundary condition is shown to correlate well with measured results for radiation patterns and resonant frequencies.     

Reflection and transmission of a dielectric waveguide mirror

A numerical analysis of a generalized dielectric waveguide mirror of arbitrary structure angle is presented. A plane wave expansion technique is used to calculate output angle, power transmission, inter-waveguide and intra-waveguide coupling, far-field emission profile and losses of the waveguide mirror. In order to evaluate the effect of divergence, two methods are used and the result indicate that the effect is minimal. Furthermore, the introduction of a tilt in the mirror surface is examined and reveals a reduction in the inter-waveguide coupling as the tilt is increased. However, this coupling remains symmetric in tilt despite the asymmetry of the geometry due to the tilt. Results of the output angle and the FWHM (full-width half-maximum) of the emission profile are compared to experimental values obtained for a semiconductor triangular ring laser     

原子介质诱导的纠缠

提出了一个利用原子介质在光机械系统中产生纠缠的方案。研究结果表明,当腔场和原子介质间的耦合系数取合适值时,腔场和动镜,镜子与原子,以及腔场和原子之间都是纠缠的。此外,文章考虑了腔场耗散效应,并给出用“logarithmic negativity”去度量系统纠缠的数值解。     

THE INVERSE ELECTROMAGNETIC SCATTERING OF INHOMOGENEOUS DIELECTRIC THIN TUBES

By using the method of Fourier series expansion, the inverse electromagnetic scattering problemof a 2- dimensional lossy dielectric body, of which the cross section is a narrow annulus, is studied. Theanalytic expressions of the electric parameters of a dielectric body are given in terms of the outsidesca,ttering field, and the simulative results are satisfactory.     

Ridged cavity backed slot antenna with dielectric loading

A reduced size cavity backed slot antenna, consisting of a transverse slot in the flat broadwall of a deep single ridge waveguide cavity is described. Partial dielectric loading achieves significant further reduction in electrical size. Moderate dielectric loss increases bandwidth (and significantly reduces antenna gain).<>     

Electromagnetic penetration into a rectangular cavity with multiplerectangular apertures in a conducting plane

Electromagnetic wave penetration into a rectangular cavity with multiple rectangular apertures is studied. The Fourier transform and the mode matching method are used to obtain simultaneous equations for the modal coefficients. The simultaneous equations are solved to represent the cavity field in series forms, which are suitable for numerical computations. Numerical computations are performed to investigate the field penetration into a cavity in terms of the shielding effectiveness for a various geometry     

InP-based short cavity lasers with 2D photonic crystal mirror

The authors have successfully fabricated in-plane emitting InP-based microlasers with cavity lengths of 600-100 μm. The required high reflectivity mirrors consist of a 2D ΓM-oriented triangular photonic crystal of air rods with a lattice constant of 350 nm. The lasers operate CW at room temperature with a threshold current of 29 mA and output power up to 4 mW for the shortest devices     

Characteristic mode formulation of multiple rectangular aperturesin a conducting plane with a dielectric-filled cavity

An analysis that is applicable to the general class of the apertures-fed cavity problem is presented. This formulation is done using the characteristic mode theory for aperture problems. First, a matrix equation whose solution determines the characteristic magnetic currents of the problem is derived. Finally, numerical results for two apertures example are presented to illustrate the generality and the simplicity of the formulation     

Frequency-adjustable circularly polarised dielectric resonator antenna with slotted ground plane

Circularly polarised (CP) dielectric resonator antennas (DRAs) with a slotted ground plane are proposed. The proposed CP design is achieved by embedding two pairs of unequal slots in the finite ground plane of the feed substrate, which results in the excitation of two near-degenerate orthogonal modes and leads to CP radiation. For the proposed design, a large CP bandwidth, determined from 3 dB axial ratio, as high as 2.7% is also obtained. The resonant frequency can be tuned by changing the slot length. This proposed design is applicable to DR antennas where post-manufacturing trimming is required. Details of the proposed designs and experimental results of the constructed prototypes are presented.     

Low-profile resonant cavity antenna with artificial magnetic conductor ground plane

A planar artificial magnetic conductor (AMC) ground plane is proposed as a means to reduce the profile of a highly directive resonant cavity antenna. The structure is formed by a printed microstrip patch antenna and a superimposed partially reflective surface. The antenna profile is reduced to approximately half by virtue of employing the AMC ground plane. A ray theory model is used to qualitatively describe the functioning of the antenna and theoretically predict the existence of quarter wavelength resonant cavities.     

Electromagnetic scattering by a dielectric slab loaded with aperiodic array of strips over a ground plane

Scattering of electromagnetic waves from a dielectric slab loaded with a periodic array of perfectly conducting strips is analyzed by a mode-matching technique. The variation of energy of significant scattered modes with various structure parameters is presented for both principal polarizations of the incident wave. The convergence and accuracy of the numerical method is evaluated. Further numerical results are obtained to show the effects of various parameters on the distribution of power in various propagating modes. The results show the usefulness of these structures as reflection-type gratings, polarizers, and filters     

Theory and experiment of circularly polarized dielectric resonator antenna with a parasitic patch

The use of a single parasitic patch for circular polarization (CP) excitation of the dielectric resonator antenna (DRA) is investigated. For demonstration, the technique is applied to the conformal-strip fed hemispherical DRA, excited at the fundamental TE/sub 111/ mode. Using the Green's function approach, the integral equations for the conformal-strip and parasitic-patch currents are formulated by matching the appropriate boundary conditions. The equations are then solved using the method of moments (MoM). In using the MoM, both the rigorous and simplified current expansions are used for the parasitic patch, and their results are compared with each other. In each case, the impedance integrals are evaluated by virtue of newly obtained recurrence formulas and direct analytical integration. Hence, the results can be calculated very efficiently without the need for any numerical integration, which greatly facilitates the numerical implementation. The input impedance, axial ratio, and radiation patterns of the CP DRA are calculated, and the results are in good agreement with measurements.     

含介质的边界振动的微腔中薛定谔猫态的产生

采用全量子理论,考虑了边界振动的含克尔介质的微腔（振动边界视为频率为 的量子谐振子）与单模辐射场构成的系统,给出了系统的时间演化算符及其变换,得到了系统的态函数随时间的演化关系.讨论了当振动边界回到初态时的腔场态,得到了许多与已有文献不同的薛定谔猫态,这对于研究猫态的性质和应用是十分有意义的.     

60°二维指向镜的面阵相机几何模型标定方法

三轴稳定静止轨道面阵相机需要对一定视场内的目标进行搜索和跟踪,常采用二维指向镜与面阵探测器结合的"凝视"成像的技术方案。但是具有二维指向镜的面阵相机像面存在畸变和像旋等问题,影响目标跟踪定位精度。对60°二维指向镜的面阵相机进行了畸变校正和像旋校正,提出基于内外方位元素结合的几何模型实验室标定方法。通过对指向镜法线、南北轴、东西轴的共计13个误差项进行解算优化,平均误差为0.74像元,满足实际使用需求。     

Bow-tie antennas on a dielectric half-space: Theory and experiment

A new formulation is discussed for the rigorous calculation of the radiation pattern of a bow-tie antenna of finite length and infinitesimal thickness, placed on a lossless dielectric substrate. The analysis is based on a representation of the current density on the metal surface of the antenna as a sum of an imposed (quasistatic) term and a set of current modes with unknown amplitudes. Free-space fields that are expressed in terms of continuous spectra of symmetrized plane waves are matched to the current modes using the method of moments. The resulting set of equations are solved for the unknown current amplitudes. The calculations show that for increasing bow length the antenna impedance spirals rapidly to a value predicted by transmission line theory. The theory also shows that theE-plane pattern of a two wavelength,60degbow-tie antenna is dominated by low-loss current modes propagating at the dielectric wavenumber. As the bow tie narrows, the loss of the modes increases, and the dominant wavenumber tends to the quasistatic value. Pattern measurements made at 94 GHz are shown to agree well with theoretical predictions. Measurements for a long-wire antenna, a linear array of bow-tie elements, and a log-periodic antenna are also presented.     

Measurement of complex dielectric permittivity at microwavefrequencies using a cylindrical cavity

A technique is presented for measuring complex dielectric permittivity using a full field analysis of a coaxially driven cylindrical cavity. The analysis of the junction is based on a model which fully considers the coaxial form of the cavity excitation, and which has been shown to produce very accurate results for a wide range of cases. Values of permittivity predicted by this method for two materials of well known permittivity are presented     

Single-frequency fiber laser from linear cavity with loop mirror filter and dual-cascaded FBGs

A single-frequency ytterbium fiber laser was demonstrated by introducing a loop mirror filter, a polarization controller (PC), and dual-cascaded fiber Bragg gratings (FBGs) in linear laser cavity. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. The spatial hole burning effect was restrained by adjusting PC appropriately. Dual closely cascaded FBGs as the output coupler, acting as an etalon, expanded the operation range of single frequency. Output power up to 18 mW at 1064 nm were obtained under the launched pump power of 107 mW at 976 nm, the optical-optical conversion efficiency was about 16.8%; the slope efficiency was about 20%.     

Diffraction of a plane wave by a multiserial lattice located in a dielectric layer

A modified zero field method is applied to solve the 2D problem of scattering by a multiserial lattice. The lattice consists of perfectly conducting elements and is situated in a homogeneous dielectric layer. The system of integral equations is derived and formulas for calculating the reflection and transmission coefficients are obtained for various geometries of the lattice elements. To increase the efficiency of the algorithm work, both polar and elliptic coordinates are applied to choose the auxiliary contour on which the zero field condition is stipulated.