Measurement of the electric field pattern of a Fabry-Perot resonator used in quasi-optical gyrotrons

The field pattern of the resonator used in a quasi-optical gyrotron operating in the millimetre wave range is measured. Two resonators are studied: one composed of a spherical mirror and an ellipsoidal grating and the other symmetric using two mirrors with annular slots. The measurements indicate that the electric field distribution is gaussian, in spite of the complex geometry of the resonator, and thus provide an experimental basis for the assumption often used to compute the efficiency of quasi-optical gyrotrons.     

Analysis on radial field of quasi-optical power combiner using complex source point theory

A uniform high-frequency solution is presented for the diffraction by a dielectric spherical mirror by a Gauss beam. Using the complex source-point theory, the radial field of quasi-optical power combiner is obtained. The E or H plane patterns of the combiner are calculated.     

高斯反射平凹二维腔横模选择特性的有限阶矩阵分析

本文利用自再现理论,将高斯反射二维腔的衍射积分析方程转化为有限阶国方程,对高斯反射平凹二维腔的横模选择特性进行数值分析,研究结果表明,高斯反射平凹二维腔选横模的性能优越,可应用于大功率激光器,从而为激光材料表面处理提供优质的激光光束。     

Nonconfocal multimode resonators for masers

The case of a resonator composed of two concave spherical reflectors separated by an arbitrary distance is examined. The general problem of the electromagnetic field distribution over the nonconfocal aperture is first formulated by means of the Huygens principle. The solution of the resulting integral equation is obtained analytically in the highly nonconfocal limit. It was found that when the reflector spacing d is much larger than the radius of curvature b of the reflectors, the aperture field distribution is in the form of traveling waves. For arbitrary d/b, the eigenvalues and eigenfunctions of the lowest order mode is obtained by numerical solution using the IBM 7090 computer. The diffraction loss was found to increase rapidly when d→2b and a geometrical interpretation of this behavior is given. Furthermore, it was found that as the spacing departs from the confocal value, the apertures are no longer surfaces of constant phase. The optimum spacing for maximum Q of the resonator is also obtained.     

高斯镜平凸非稳腔本征模场的有限元数值计算

为了研究激光在高斯镜平凸非稳腔中的模式和相位特征,在SIEGMAN分析多元件非稳腔的理论基础上,采用有限元数值方法计算耦合输出镜镜面反射率为高斯分布的圆镜平凸非稳腔本征模场分布。将光场在腔内一次往返的ABCD系数代入惠更斯-基尔霍夫衍射积分方程,可以写出光场往返一次的衍射积分方程。将镜面分割成若干个等宽圆环,把衍射积分方程转化成矩阵相乘形式,经过数值计算,得到理想空腔和非共轴空腔优先起振的光场本征模式分布结果与相位特性。计算结果表明,当合适选择输出镜半径与高斯反射率分布,可以得到光斑半径为0.3cm的基模高斯光束输出,此计算结果与实验结果相符。同时也讨论了耦合输出镜对光束质量的影响。     

Electrostatic mirror objective with eliminated spherical and axial chromatic aberrations

Computational formulae for the coefficients of the third-order spherical aberration and the second-order axial chromatic aberration are presented for an axially symmetric electrostatic electron mirror. A technique for eliminating the high-order derivatives of the potential axial distribution in mirror systems from the integrands is described. Conditions for elimination of spherical and axial chromatic aberrations, either separately or simultaneously, are found for a three-electrode axially symmetric mirror composed of coaxial cylinders of the same diameter. A principal scheme of the transmission electron microscope, where an electrostatic electron mirror serves as its objective, is presented.     

高斯反射率方形平凹腔激光模场的有限元分析

利用柯林斯公式和边界有限元方法，将方形球面镜腔的衍射积分方程转化为矩阵方程，并对高斯反射率方形平凹腔的模场分布进行了数值计算。研究结果表明，高斯反射率方形平凹腔具有较好的选模性能，可以应用于高功率激光器以获得高质量的激光光束。     

用于回旋速调管的新型开放式球形谐振腔

作为毫米波、亚毫米波源的回旋速调管工作于W波段及以上波段时,如何提高输出功率和工作效率是回旋管研究的重点.对开放式球形腔TE谐振模式的特点进行了理论分析,并与圆柱谐振腔TE模式进行了比较,通过计算模拟对比了二者谐振腔的电场能量分布特点.与圆柱谐振腔TE021模式相比,在电子通过区域,开放式球形腔内TE102谐振模的高频...     

非链式DF激光器非稳腔数值仿真与实验

基于描述光束传播的菲涅耳-基尔霍夫衍射积分理论,运用快速傅里叶变换算法仿真了非稳腔DF激光的三维近场、远场光强分布。仿真结果显示:非稳腔的近场输出光斑形状为中心对称的空心圆环,远场输出光斑为具有中心亮斑的多级衍射环;大M数将导致近场光斑能量集中,大的Neq值将引起远场发散角变大。运用该算法研究了腔镜倾斜对近场光强分布的影响:腔镜倾斜使光束近场分布变差,倾斜角越大,光强的非对称分布越明显。开展了非链式DF激光器非稳腔实验研究,实验得到的近场、远场光强分布及腔镜失调下的近场光斑变化情况与数值模拟结果一致,实验测量的远场发散角为1.2 mrad。文中的仿真结果可为DF激光器腔镜失调诊断及调节提供依据。     

Analysis of steady-state cascaded stimulated Brillouin scatteringin a fiber Fabry-Perot resonator

We investigate the steady-state properties of cascaded stimulated Brillouin scattering (CSBS) in a fiber Fabry-Perot resonator with reflection mirrors by numerically solving the coupled-power equations under the boundary conditions at the two mirrors. The dependence of CSBS on the input power is calculated for the symmetric and asymmetric fiber resonators. The threshold powers for the first- and second-order Stokes waves are calculated as a function of the mirror reflectance for the symmetric resonator     

Magnetodynamical modes in a spherical ferrite cavity

The axial-symmetrical modes of a spherical cavity containing magnetised-ferrite material are calculated. It can be shown that the different modes of the resonator are coupled by the gyrotropic medium. The field of the gyrotropic resonator is represented by an infinite sum of the eigenfunctions of the spherical resonator containing an isotropic medium. Under consideration of the boundary conditions the dependence of the resonance frequency on the magnetic-bias field may be obtained.     

Millimeter-Wave Power Combiner Using Quasi-Optical Techniques

A millimeter- or submillimeter-wave combiner using a quasi-optical open resonator to effectively combine the power output of several solid-state oscillators to a single-frequency is described. The combiner makes use of a symmetrical concave spherical resonator with dielectric wedge launchers as energy couplers. To demonstrate feasibility of this concept, experiments were carried out by using two InP Gunn oscillators at 60 GHz, and a combining efficiency of 54 percent has been achieved.     

稳定型准光腔外衍射场计算

稳定型准光腔外衍射场的计算是实现准光功率合成与天线一体化设想的关键性问题。本文在A.L.Cullcn提出的准光腔复源点理论和L.B.Felsen提出的复射线理论基础上结合几何分析和计算,得到了E和H平面远区方向性图。本文的计算与实验结果基本吻合。     

一种基于微带开口环的双通带滤波器设计

文中提出了一种基于微带开口环的双通带滤波器设计,对比了非对称开口环结构与传统对称结构的传输特性,讨论了非对称结构中两端馈线位置,双环耦合间距以及环线宽度对于滤波器性能的影响,然后在此基础上,利用两级级联耦合开口环设计了一个用于接收机中抑制镜像的双通带滤波器,带外抑制度较高。     

On the Complex Resonant Frequency of Open Dielectric Resonators

An analytical method is presented for calculating accurately the complex resonant frequency of dielectric pillbox resonators. In this method, an approximated field of the resonator is expanded into a truncated series of solutions of the Hehnholtz equation in the spherical coordinates, and the boundary condtion on the resonator surface is treated in the least-squares sense. The resonant frequency and the intrinsic Q value due to radiation loss are obtained in the form of approximation converging to the exact values. Numericaf results are compared with previously published calculations, which show that the present method is a relatively simple and effective one.     

Study on InGaAsP-InGaAs MQW-LD with symmetric and asymmetric separate confinement heterostructure

We studied symmetric and asymmetric InGaAsP-InGaAs 1.55-/spl mu/m multiquantum-well (MQW) laser diodes (LDs) with highly p-doped layers in the two-step separate confinement heterostructure (SCH). The p-doping in p-SCH suppresses the electron overflow from the MQWs to p-SCH, but it is an origin of free carrier absorption loss. An additional InGaAsP layer inserted inside n-SCH makes asymmetric field distribution and, therefore, reduces the portion of optical field distribution in highly p-doped regions with high optical loss. Compared with symmetric structure, asymmetric SCH LD has low threshold current density, low internal loss, and high and flat slope efficiency with respect to temperature.     

圆形镜共焦腔模式分布的有限元数值计算

利用有限元法,对圆形镜共焦腔的模式分布进行数值计算,结果表明：当菲涅尔数较小时,最低损耗模式为低阶模,而菲涅尔数较大时,优先起振的模式为高阶模。     

一种新型广义交叉耦合滤波器的设计

含广义交叉耦合的N个谐振器滤波器,即含源-负载交叉耦合的滤波器能产生N个传输零点,通过给出这种滤波器的等效网络模型和传输函数,设计了两种新颖六边形结构的含源-负载交叉耦合的微带滤波器,一种为对称结构,一种为非对称结构.对其进行了仿真分析,仿真结果与理论值吻合较好.与传统两腔发夹形滤波器相比,这种两腔六边形结构的滤波器尺寸要缩小27.5%,频率选择性更高.     

Investigation on spectral behaviour of novel direct coupling compound fibre ring resonator

A novel compound fibre ring resonator based on direct coupling rather than fibre loop reflectors is presented. Its performance under symmetric and asymmetric operation is investigated.<>     

非轴对称腔板条固体激光器

本文使用复曲率张量Q-1自再现法分析了柱面-球面镜非轴对称腔的特性,并用数值计算例说明。报导和讨论了我们的非轴对称腔板条固体激光器的实验结果。