Simulation of IR Waveguide Amplifiers Using FDTD-Based Overlapping Integral-RK Method

A novel algorithm, calling FDTD-based overlapping integral-RK method, is proposed to analyze Er-Yb co-doped phosphate glass IR waveguide amplifiers. This new method is derived from the combination of Finite-Difference Time-Domain(FDTD), overlapping integral and RK method. First the normalized eigen-fields of signal and pump lights in Er-Yb co-doped phosphate glass waveguide are calculated by FDTD algorithm, and then the overlapping integrals between light fields and the distribution of Er³⁺(Yb³⁺) concentrations are obtained, finally the distributions of powers of signal and pump along waveguide are calculated by RK method. Gain performance of IR waveguide amplifiers is obtained from calculated signal power. Comparison of the simulation result with an experiment is given, it demonstrates that this new algorithm is valid and shows good agreement with experimental results.     

A Noteworthy Trap in Using the EDC Method for Solving Dielectric Waveguide Problems

EDC method is probably the simplest method to obtain a good approximation for the propagation constant of a dielectric waveguide. It is well know that there are two ways to perform the EDC procedure: one is to treat the LSE mode first then the LSM mode and the other is just reverse. It is true that the difference between the results got from the two ways is usually rather small and thus both of them are good approximations. In this paper, we show that in some cases the two ways will lead to much different results; one is still a good approximation while the other is completely unacceptable. The theoretical analysis tells us that if performing the LSM mode first then with the LSE mode will usually get a good result.     

Source Localization in an Acoustic Waveguide with Inaccurately Known Parameters Using Matched Processing in the Mode Space

Acoustical Physics - An adaptive modal MUSIC algorithm is constructed to localize an acoustic source by a vertical array operating under conditions of incomplete information on a waveguide...     

Analysis of the Scattering Characteristic of Several Waveguide Components Using Boundary Element Method

Several kinds of waveguide components such as curved waveguide bends, arbitrary angle waveguide bends and T-junctions have been analyzed with boundary element method in this paper. A new discretization method for the boundary element method to solve the waveguide discontinuities has been given. The numerical results obtained agree well with the experimental results and numerical results in other literature. Especially, the scattering characteristics of Forded E-, H-plane T-junctions in 3mm band have been analyzed using boundary element method and the calculation results are presented.     

Absorption Measurement Using a Leaky Waveguide Mode

We propose an optical waveguide sensor using a leaky mode for absorption measurement of liquid samples. This sensor uses a single coupling prism. A cladding layer and a waveguide layer are directly deposited on the reflecting surface of the prism. The intensity of the internally reflected beam at an appropriate incident angle is very sensitive to the imaginary part of the sample attached to the surface of the waveguide layer. The sensitivity of this sensor is controlled by the thicknesses of both cladding and waveguide layers. We studied the performance of the sensor by numerical calculation.     

Tomographic Estimation of Waterbody Parameters in the Presence of Ice Cover Using Seismoacoustic Sources

Acoustical Physics - The article presents the results of field tests of marine seismic sources and seismoacoustic areal measuring systems based on autonomous embedded buoys in Lake Ladoga under ice...     

光波导技术同步测量棱镜及波导薄膜参数

依据全反射理论和棱镜耦合原理,实现了对棱镜折射率及波导薄膜材料折射率和厚度的同步测量。使用高准直半导体激光器激光入射到棱镜内部与波导膜的分界面上,逐步旋转棱镜或改变棱镜的入射角,得到棱镜耦合M线,曲线前面几组的波谷为波导模激发,在M线左侧收尾处有一个不完整波峰,其反射光强随入射角迅速衰减,为全反射时的临界点,由此可实现棱镜及波导薄膜参数的同步测量;用此法测量了棱镜耦合一体化平面波导棱镜的折射率和聚甲基丙烯酸甲酯(PMMA)聚合物波导薄膜的折射率和厚度。测量棱镜折射率精度为±1.9×10-4,波导薄膜折射率和厚度的精度分别为±6.2×10-4 μm和±1.6×10-2 μm。     

Recovery of the Characteristics and Determination of the Parameters of Statistical Nanometer Surface Roughness Using the Data on Scattering in a Planar Optical Waveguide

We consider the problem of scattering of a guided TE-mode in a planar optical waveguide with small random irregularities. The results of numerical solution of the direct and inverse problems of waveguide scattering for a statistical stationary nanometer surface roughness are presented. We show the possibility of retrieving information on the statistical properties of the surface roughness from scattered-radiation measurements in the far region (or in the equivalent Fourier plane). It is found that superresolution can be reached in a roughness correlation range of about /30-/20 for high signal-to-noise ratios by optimizing the optical-transfer function and efficient smoothing.     

Modal Analysis of Nonuniformly Dielectric Waveguide Using Semivectorially Compact Finite-Difference Time-Domain Method

A compact two-dimensional finite-difference time-domain method is developed for the modal analysis of nonuniform dielectric waveguides. The unsplit-field perfectly-matched-layer absorbing boundary condition has also been extended to this approach. The proposed method approximates the maxwell equations by using the semivectorial wave equations, and the dominant electric fields are solved for two perpendicular polarizations. By introducing the new techniques, complex variables can be avoided in the calculations. At the same time, the number of variables is minimized in the computation domain. Through that, approximately half of the computation effort can be saved without accuracy loss. Numerical examples are given to substantiate the theory. Excellent accuracy has been obtained for the entire frequency spectrum, even near the cutoff region.     

Spectrofluorimetric Estimation of Norepinephrine Using Ethylenediamine Condensation Method

A simple and sensitive method for the determination of norepinephrine is described. Norepinephrine (NE) was oxidized by mercury (II) nitrate and the oxidation product was condensed with ethylenediamine (EDA) to form a strong fluorescent compound. The addition of acetone enhances the light intensity. The measurement was carried out at 507 nm with excitation at 420 nm. A linear relationship was obtained between the fluorescence intensity and norepinephrine concentration in the range of 0.01 μM–0.014 mM; the correlation coefficient and the detection limit are 0.99813 and 2.5 nM, respectively. The interference from dopamine (DA) can be eliminated by first derivative synchronous fluorimetric method using peak to zero technique. The recovery efficiency was performed using known amounts of norepinephrine in urine sample and the results indicate a 95–98.62% recovery. The proposed method was also applied to the determination of norepinephrine in injections solution. The reaction mechanism was also described.     

Method of Designing a Corrugated Optical Waveguide Filter

The method of designing a corrugated optical waveguide filter is proposed to yield an arbitrary spectral profile of the reflection coefficient. It gives the functional dependence of the corrugation depth on distance along the wave propagation direction. The basis of the theory of the method is a combination of the effective index approach and the Fourier transformation technique. It represents the spectral profile of the reflection coefficient approximately to Fourier transformation of the spatial profile of the effective refractive index. Examples are presented to illustrate how to apply the technique.     

Estimation of Markov Sequences with Jump-Like Variation of Parameters by the Interpolation Method

Using the methods of the theory of optimal nonlinear filtering, we develop an algorithm for obtaining optimal estimates of the sequence of hidden states of discrete-valued Markov processes with abruptly changing parameters at unknown time. Optimal estimates of the states of Markov processes and of the time of appearance of an abrupt change in parameters are obtained as a result of interpolation by processing the entire observation sequence. The results of simulation of the algorithm work are presented. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 628–639, July 2005.     

Source Localization in a Non-Uniform Acoustic Waveguide Using the Modal Rank-Reduction Algorithm

Radiophysics and Quantum Electronics - We constructed an adaptive modal rank-reduction algorithm for acoustic source localization with a vertical sensor array operating under conditions of...     

Estimation of the Parameters in a Two-State System Coupled to a Squeezed Bath

Estimation of the phase and weight parameters of a two-state system in a squeezed bath by calculating quantum Fisher information is investigated. The results show that, both for the phase estimation and for the weight estimation, the quantum Fisher information always decays with time and changes periodically with the phases. The estimation precision can be enhanced by choosing the proper values of the phases and the squeezing parameter. These results can be provided as an analysis reference for the practical application of the parameter estimation in a squeezed bath.     

基于极大似然估计法求解微燃机特性反问题

发展了一种基于极大似然估计法求解微燃机特性反问题的方法.构建了微燃机全工况模型和反问题求解方法.为对上述模型和方法进行验证,将模拟数据加上测量误差作为反问题的求解条件,反推了单元部件额定效率和压气机特性模型参数.结果表明,单元部件额定效率估计值与原给定值差别较小,压气机特性模型能够较好地表达压气机特性线信息.     

A Parameter Estimation Method Using Linear Response Statistics

This paper presents a new parameter estimation method for Itô diffusions such that the resulting model predicts the equilibrium statistics as well as the sensitivities of the underlying system to external disturbances. Our formulation does not require the knowledge of the underlying system, however, we assume that the linear response statistics can be computed via the fluctuation–dissipation theory. The main idea is to fit the model to a finite set of “essential” statistics that is sufficient to approximate the linear response operators. In a series of test problems, we will show the consistency of the proposed method in the sense that if we apply it to estimate the parameters of the underlying model, then we must obtain the true parameters.     

Diffraction of an Electromagnetic Wave on a Dielectric Rod in a Rectangular Waveguide. A Method of Partial Waveguide Filling

Russian Physics Journal - A variant of the method of partial waveguide filling is considered in which a sample is put into a waveguide through holes in wide waveguide walls at the distance equal to...     

Application of Davidenko''s Method to a Lossy Nonlinear Waveguide

Davidenko's method is implemented for determining the complex propagation constants (Modal index and attenuation coefficient) of nonlinear TE waves guided by an asymmetrical lossy nonlinear dielectric wave-guide. The waveguide structure has a generalized nonlinear substrate with a permittivity of the form | E |and an absorbing cover making the propagation constant to be complex. Davidenko's method shows to be a fast and accurate analysis in finding the complex propagation constants. The effects of initial condition parameter on the propagation characteristics are investigated, analyzed and discussed.     

Determination of the Source Bearing in a Waveguide by Using the Sound Field Interference Pattern

The feasibility of determining the source bearing in a waveguide by an extended horizontal line array with the use of the sound field interference pattern is studied. The sound field is generated by an omnidirectional monochromatic point source and is represented as a sum of modes. The case of a small number of lowfrequency modes is considered.