Selectivity of dispersive resonators with stochastic inhomogeneities

A set of equations is derived for the analysis of the selective properties of dispersive resonators with stochastic irregularities. The dependence of the resonator spectral function on the statistical parameters of a stochastic phase screen and on the transmission function form of the diaphragm is studied. The inhomogeneities are shown to change the form of the selectivity function for a diaphragm with constant transmission coefficient, whereas they only lead to general loss increase for a parabolic dependence of the transmission coefficient.Scientific-Engineering Center for the Automation of biotechnical Systems, Sonar, Ukrainian National Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 3, pp. 330–339, March, 1994.     

Graded reflectivity mirror unstablelaser resonators

The graded reflectivity mirror (GRM) unstable resonator has become the resonator of choice for many solid-state laser systems. This tutorial review discusses through a step-by-step approach the inner workings of such resonators, in order to identify for potential designers and users tradeoffs which are involved in their design. Geometrical and diffractive contributions to the mode definition are discussed using a canonical formulation applicable to all types of unstable resonators. Particular attention is given to super-Gaussian resonators, which are nowadays the most widely used. The beam-shaping action of an amplifying medium is illustrated through a practical example, which makes clear the necessity to use a proper simulation software to predict correctly the behaviour of the resonator. This revised version was published online in November 2006 with corrections to the Cover Date.     

Open resonators with thin dielectric plates

We develop the approximate theory of the open resonator with spherical mirrors and a thin dielectric plate. The dependences of eigenfrequencies on the dielectric permittivity of the plate and its thickness are determined. It is shown that in the case where the plate is located in the resonator midplane, the dependences of eigenfrequencies of even and odd modes on the plate thickness are significantly different. The developed theory is used to measure the dielectric permittivity of thin plates. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 219–226, March 2006.     

Electromagnetic characterization of rectangular ferroelectric resonators

An optimized geometry for a rectangular ferroelectric resonator (FR) is proposed to increase signal-to-noise ratio in EPR spectroscopy. To develop optimization criteria, the distribution of the microwave electromagnetic field in the FR is computed and analyzed. The computations, based on solution of Maxwell's field equations, were made for two types of rectangular FRs-a FR with a hollow sample hole and a FR with a blind sample hole. To introduce the samples, a hole was drilled through the resonator with its axis aligned to the axis of the FR. We computed and studied the spatial distributions of H- and E-components of the microwave electromagnetic field for two rectangular FRs, made of single-crystal potassium tantalate, with the following sizes: 1.9 x 1.9 x 1.4mm(3) and 1.7 x 1.7 x 3.1mm(3). As analysis of the obtained data indicated, in both resonators, the lowest mode was TE(11delta). By analyzing the distribution of the microwave field in the FR and comparing it with the experimental result, we developed optimization criteria for the geometry of a rectangular FR.     

角隅全反镜谐振腔激光器的输出特性

 在高功率脉冲气体激光器中,用角隅反射镜作为全反镜,平行平面镜作为输出镜构成角隅全反镜谐振腔。对角隅腔激光器的输出特性和抗失调稳定性进行了研究,并与平凹腔和平平腔激光器进行了比较。实验结果表明：在角隅全反镜失调角为16 mrad时,角隅腔激光器的单脉冲输出能量下降9.2%,且近场输出光斑没有明显变化;而凹面全反镜失调角仅为0.4 mrad时,平凹腔激光器输出能量下降了9%,近场输出光斑严重变形。在输出镜正前方3.12 m处测量,当角隅镜偏转16.3 mrad时,激光器输出光斑与标准状态时的输出光斑重合;凹面全反镜失调角为0.4 mrad时,激光器输出光斑位移14 mm。经模式仪分析表明,角隅腔激光器近场光强分布均匀。     

角隅全反镜谐振腔激光器的输出特性

在高功率脉冲气体激光器中,用角隅反射镜作为全反镜,平行平面镜作为输出镜构成角隅全反镜谐振腔。对角隅腔激光器的输出特性和抗失调稳定性进行了研究,并与平凹腔和平平腔激光器进行了比较。实验结果表明：在角隅全反镜失调角为16 mrad时,角隅腔激光器的单脉冲输出能量下降9.2%,且近场输出光斑没有明显变化;而凹面全反镜失调角仅为0.4 mrad时,平凹腔激光器输出能量下降了9%,近场输出光斑严重变形。在输出镜正前方3.12 m处测量,当角隅镜偏转16.3 mrad时,激光器输出光斑与标准状态时的输出光斑重合;凹面全反镜失调角为0.4 mrad时,激光器输出光斑位移14 mm。经模式仪分析表明,角隅腔激光器近场光强分布均匀。     

Coupling frequencies of rectangular waveguide-dielectric resonators partially filled with dielectric

The partial-region method is employed to solve the problem of quasinatural mode H_n0(p+) of coupled waveguide-dielectric resonators with axially and centrally symmetric placement of inserts in an overmoded waveguide. Good agreement is obtained between the calculated and experimental results. The dynamics of coupling-frequency behavior is studied.Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, Nos. 3, 4, pp. 356–362, March–April, 1992.     

Cylindrical Gaussian-Hermite modes in rectangular waveguide resonators

Approximate solutions to the wave equation inside a rectangular metallic waveguide has been obtained in terms of cylindrical Gaussian-Hermite functions.E _mn ^π modes propagate with negligible straight guide losses in the far-infrared region. A new type of low-loss optical resonator suitable for FEL operation at long wavelengths is presented here.     

长条形镜面面形拟合技术研究

为了解决长条形镜面面形拟合中各项不正交,无法在调整中利用像差指导计算机辅助装调的问题,本文建立了一套合理的拟合模型。该模型以矩阵求解正交化Zernike多项式系数为基础,将离散的数据点作为定义域,对已选取的Zernike项进行定义域内正交化计算,并以获得的各正交项为基底,实现对长条形镜面及其他异形光学镜面的正交化多项式拟合求解。进而确定在干涉检测中加工误差与装调误差的分离,为光学镜面的最终面形收敛提供保障。根据本文实验结果,对一口径600 mm×260 mm,PV与RMS值分别为5. 889λ及1. 002λ的长条形光学镜面进行拟合,利用Metropro去像散后,面形未得到收敛,PV与RMS值分别变为7. 448λ及1. 725λ。而采用本文算法处理后,其PV与RMS值分别收敛为4. 666λ及0. 679λ,验证了本文方法对于长条形镜面拟合的正确性。     

Mode profiles in resonators with a near 90° roof-top mirror

The transverse modes of a laser resonator comprising a near 90° roof-top mirror and a feedback mirror are studied theoretically. We relate this configuration to an almost plane roof-top resonator and apply the Fox and Li technique to compute the lowest-order symmetric and antisymmetric modes. The effects of perturbations to the vertex angle of the roof-top mirror, misalignments of the feedback mirror and curved feedback mirrors are examined.     

Thermoelastic damping in rectangular and circular microplate resonators

Predicting thermoelastic damping (TED) is crucial in the design of high Q micro-electro-mechanical systems (MEMS) resonators. In the past, some analytical models have been developed for TED in microbeam resonators. Rectangular and circular microplates are also common elements in many micro-resonators. Two analytical models have been developed for TED in the contour-mode vibration and the out-of-plane vibration of circular microplates, respectively. However, there is lack of works that model the TED in the out-of-plane vibration of rectangular microplates. This paper presents an analytical model for the TED in the fully clamped and simply supported rectangular microplates. The quality factor is found by calculating the energy dissipated per cycle of vibration over the volume of the microplate. The derivation in this paper shows that the model for the TED in the fully clamped and simply supported rectangular plates is the same as the model for the TED in the fully clamped and simply supported circular plates. For the rectangular microplates with other boundary conditions, based on Rayleigh's method, this paper presents a set of analytical approximate models to estimate the TED in the rectangular microplates vibrating in the fundamental mode. The present model is validated by comparison with previously reported model and the FEM model.     

轻微非共面腔的输出片应力作用研究

 建立了计算轻微非共面腔输出光椭圆度的数学模型,分析了R. H. Moore专利中的理论计算错误,计算分析了输出片的应力作用对输出光椭圆度的影响,发现：输出镜片的应力作用对环形激光器顺时针方向和逆时针方向输出光椭圆度的非对称有影响。通过实验验证了理论计算的正确性。得出R. H. Moore, S. W. Hammons等人在专利中提出的调腔方法存在错误,它不能有效地消除环形激光器中由腔体轻微异面所引起的磁效应。     

Open resonators for low dielectric loss measurements

Open resonators are studied based on the scattering theory. In particular, a theory of open resonators with a dielectric plate is constructed. This theory is used to develop a technique for measuring small dielectric loss. Measurements of the loss tangent in diamond plates show that the volume absorption in the best samples is ≈7×10^?6 in the high-frequency part of the millimeter-wave range. A significant absorption in thin surface layers that is caused by surface treatment techniques (polishing, vacuum soldering, etc.) is revealed.     

长条形反射镜体轻量化结构的参数优化设计

提出了一种对长条形反射镜轻量化结构进行优化设计的方法。利用ANSYS软件建立反射镜体结构的参数化模型,将有关结构参数变量指定为优化设计变量,以反射镜体在地面重力作用下的镜面变形误差以及在承受发射过载时所产生的最大VonMises应力作为约束条件,结合有限元法对镜体轻量化结构的尺寸参数进行优化分析,得到了轻量化程度高,镜面变形误差完全满足设计要求的反射镜体。