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1.
A full-vectorial (FV) analysis of optical dielectric waveguide bends by using finite difference (FD) method in terms of magnetic field components is developed in a local cylindrical coordinate system. The perfectly matched layer absorbing boundary conditions via the complex coordinate stretching technique are incorporated into the FV wave equations for effectively demonstrating the leaky nature of waveguide bends, and a six-point FD scheme is constructed to approximate the cross-coupling terms for improving the convergent behavior. The leaky modes of a typical rib waveguide bend are calculated and the complex propagation constants and the field patterns for TE- and TM-like modes are obtained. Solutions are good agreement with those from the film mode matching method, which shows the validity and utility of the established method. 相似文献
2.
A full-vectorial mode solver in terms of the transverse magnetic field components for optical waveguides with transverse anisotropy is described by using the multidomain spectral collocation method based on Chebyshev polynomials. The waveguide cross section surrounded by the perfectly matched layers is divided into suitable number of homogeneous rectangles, and then connected with by imposing the continuities of the longitudinal field components at the dielectric interfaces shared by the adjacent rectangles, resulting in a generalized matrix eigenvalue problem. To validate the established method, results of an anisotropic square waveguide and a magnetooptic rib waveguide are presented and compared with those from the full-vectorial finite difference method, full-vectorial beam propagation method, and the experimental data. 相似文献
3.
W.-P. Zang J.-G. Tian Z.-B. Liu W.-Y. Zhou F. Song C.-P. Zhang 《Applied physics. B, Lasers and optics》2006,82(1):99-104
A high-accuracy finite-difference beam-propagation method (HAFD-BPM) based on high-accuracy divided-difference formulas is
presented. The truncation error in this HAFD-BPM is reduced to o(Δr)4in the transverse direction, whereas the error in a conventional FD-BPM is typically o(Δr)2. Gaussian beam propagation in vacuum and nonlinear medium is simulated by this new method and conventional one. The comparison
between them in computing time and accuracy reveals the advantage of this new method. As an example, this method is applied
to the simulation of blow-up in self-focusing of a Gaussian beam.
PACS 42.65.Hw; 42.25.Bs; 02.70.Bf 相似文献
4.
与介质光子晶体相比,金属光子晶体的带隙特性在毫米波和亚毫米波波段有着重要的应用价值.基于Yee网格的频域有限差分法推导得出的本征模方程,求解后能方便而又可靠地得出介质光子晶体的带隙图和场分布.但由于金属与介质的本质差异,该方法不能直接应用于金属光子晶体.文中引入了金属表面边界条件,推导了二维金属周期结构的光子带隙本征模方程.通过数值计算,得出了不同晶格结构(正方/三角格子)下两种模式(TE/TM)的全禁带特性,并与介质周期结构的禁带特性进行对比,分析了金属周期结构在模式选择和器件集成方面的优点. 相似文献
5.
与介质光子晶体相比,金属光子晶体的带隙特性在毫米波和亚毫米波波段有着重要的应用价值.基于Yee网格的频域有限差分法推导得出的本征模方程,求解后能方便而又可靠地得出介质光子晶体的带隙图和场分布.但由于金属与介质的本质差异,该方法不能直接应用于金属光子晶体.文中引入了金属表面边界条件,推导了二维金属周期结构的光子带隙本征模方程.通过数值计算,得出了不同晶格结构(正方/三角格子)下两种模式(TE/TM)的全禁带特性,并与介质周期结构的禁带特性进行对比,分析了金属周期结构在模式选择和器件集成方面的优点.
关键词:
金属光子晶体
频域有限差分法
全禁带 相似文献
6.
A finite difference scheme based on the polynomial interpolation is constructed to solve the quasi-vector equations for optical waveguides with step-index profiles. The discontinuities of the normal components of the electric field across abrupt dielectric interfaces are taken into account. The numerical results include the polarization effects, but the memory requirement is the same as in solving the scalar wave equation. Moreover, the proposed finite difference scheme can be applied to both uniform and non-uniform mesh grids. The modal propagation constants and field distributions for a buried rectangular waveguide and a rib waveguide are presented. Solutions are compared favorably with those obtained by the numerical approaches published earlier. 相似文献
7.
Uwe Langbein Udo Trutschel Andreas Unger Michel Duguay 《Optical and Quantum Electronics》2009,41(4):223-233
A rigorous mode solver for multilayer fiber configurations using a Constraint Optimization method is presented. For an arbitrary
number of dielectric or metallic layers the cylindrical wave equations are solved exactly. The transition between the different
layers implies a coupling of all field components. Case examples of three unconventional fiber structures (Air-ARROW-fiber,
metal-coated fiber, core to ring fiber coupler) are presented. Mode dispersions charts and field characteristics are calculated
to demonstrate the performance of the constraints optimization method applied. 相似文献
8.
A modified full-vectorial finite-difference beam propagation method based on H-fields in solving the guided-modes for optical waveguides with step-index profiles is described. The propagation is split into two substeps. In the first substep, the field propagates in the absence of the cross-coupling terms, and then they are evaluated and double used in the second substep. An improved six-point finite-difference scheme is constructed to approximate the cross-coupling terms along the transverse directions. By using the imaginary-distance procedure, the field patterns and the normalized propagation constants of the fundamental modes for a buried rectangular waveguide and rib waveguide are presented, and the hybrid nature of the full-vectorial guided-modes is demonstrated. Solutions are in good agreement with the benchmark results from film mode matching method, which tests the validity and utility of the present method. 相似文献
9.
Frequently the cross-section of a longitudinally homogeneous dielectric waveguide may be decomposed into rectangles with constant
permittivity. For points inside these rectangles the wave equation for modal fields is solved analytically by expanding into
functions with harmonic or exponential dependence on the transverse coordinates. Minimization of a least-squares expression
for the remaining misfit on the boundary lines allows us to determine propagation constants and fields for guided modes. Semivectorial
calculations for two sets of rib waveguides and the centre sections of a directional coupler and an MMI device show very good
agreement with results found in the literature.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
10.
Guowu Zheng Kangshen Chen 《International Journal of Infrared and Millimeter Waves》1992,13(9):1421-1431
In this paper, a full-wave two dimensional Finite-Difference-Time-Domain method in cylindrical coordinate system is developed, in which the arch is chosen as the difference cell. It is proved that the method is efficient and economical in both CPU time and temporary storage requirement, and potentially useful for the numerical analysis of dispersion of cylindrical guidewave structure. the numerical results, including the dispersive curves of the cylindrical single microstrip line and the coupled microstrip line are presented. 相似文献
11.
In this paper a time fractional Fourier law is obtained from fractional calculus. According to the fractional Fourier law, a fractional heat conduction equation with a time fractional derivative in the general orthogonal curvilinear coordinate system is built. The fractional heat conduction equations in other orthogonal coordinate systems are readily obtainable as special cases. In addition, we obtain the solution of the fractional heat conduction equation in the cylindrical coordinate system in terms of the generalized H-function using integral transformation methods. The fractional heat conduction equation in the case 0<α≤1 interpolates the standard heat conduction equation (α=1) and the Localized heat conduction equation (α→0). Finally, numerical results are presented graphically for various values of order of fractional derivative. 相似文献
12.
L.H. Liu L. Zhang H.P. Tan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,97(3):446-456
In graded index medium, the ray goes along a curved path determined by Fermat principle, and the curved ray-tracing is very difficult and complex. To avoid the complicated and time-consuming computation of curved ray trajectory, the methods not based on ray-tracing technique need to be developed for the solution of radiative transfer in graded index medium. For this purpose, in this paper the streaming operator along a curved ray trajectory in original radiative transfer equation for graded index medium is transformed and expressed in spatial and angular ordinates and the radiative transfer equation for graded index medium in cylindrical and spherical coordinate systems are derived. The conservative and the non-conservative forms of radiative transfer equation for three-dimensional graded index medium are given, which can be used as base equations to develop the numerical simulation methods, such as finite volume method, discrete ordinates method, and finite element method, for radiative transfer in graded index medium in cylindrical and spherical coordinate systems. 相似文献
13.
14.
For optical waveguides with high index-contrast and sharp corners, existing full-vectorial mode solvers including those based on boundary integral equations typically have only second or third order of accuracy. In this paper, a new full-vectorial waveguide mode solver is developed based on a new formulation of boundary integral equations and the so-called Neumann-to-Dirichlet operators for sub-domains of constant refractive index. The method uses the normal derivatives of the two transverse magnetic field components as the basic unknown functions, and it offers higher order of accuracy where the order depends on a parameter used in a graded mesh for handling the corners. The method relies on a standard Nyström method for discretizing integral operators and it does not require analytic properties of the electromagnetic field (which are singular) at the corners. 相似文献
15.
The mode expansion propagation method is a modelling technique for a large variety of waveguide components. Until now only the case with TE modes has been reported; we give details on the mode expansion propagation method for TM modes. Instead of one type of overlap integral in the TE case, a TM analysis requires two kinds of overlap integrals. The inclusion of radiation modes in this method is discussed. The modifications in the algorithm to include waveguides with gain or loss structures are also considered.As an example, the method was used for analysing a grating-assisted codirectional coupler. In particular, the radiation loss is calculated and compared with calculations when TE modes, instead of TM modes, propagate through the codirectional coupler. The radiation losses are found to be much higher for TM modes. 相似文献
16.
We analyze the microcavity waveguides and derive the coupling constant based on the coupled mode theory. The formula contains only two parameters with clear physical meanings, the quality factor of the cavity modes and the phase shift that the lightwave acquires when tunnelling between two cavities. It provides an easy way to express and modulate the properties of the waveguides. Our analytical results are supported by the simulations using the transfer matrix method. 相似文献
17.
Full-vectorial finite-difference beam propagation method based on the modified alternating direction implicit method
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A modified alternating direction implicit algorithm is proposed to solve the
full-vectorial finite-difference beam propagation method formulation based
on $H$ fields. The cross-coupling terms are neglected in the first sub-step, but
evaluated and doubly used in the second sub-step. The order of two sub-steps
is reversed for each transverse magnetic field component so that the
cross-coupling terms are always expressed in implicit form, thus the
calculation is very efficient and stable. Moreover, an improved six-point
finite-difference scheme with high accuracy independent of specific
structures of waveguide is also constructed to approximate the
cross-coupling terms along the transverse directions. The imaginary-distance
procedure is used to assess the validity and utility of the present method.
The field patterns and the normalized propagation constants of the
fundamental mode for a buried rectangular waveguide and a rib waveguide are
presented. Solutions are in excellent agreement with the benchmark results from
the modal transverse resonance method. 相似文献
18.
《Current Applied Physics》2020,20(2):244-248
We theoretically demonstrate a broadband mode converter and multiplexer based on plasmonic waveguides loaded with structured dielectrics. The proposed device can realize conversions between a fundamental TM0 mode and a first order TM1 mode, as well as (de)multiplex them with another TM0 mode. Our design exhibits as wide as 400 nm bandwidth and as short as 6~7 μm coupling length. This work has potential application in high density photonic integrated devices for both computing and communication applications. 相似文献
19.
20.
In atomic,molecular,and nuclear physics,the method of complex coordinate rotation is a widely used theoretical tool for studying resonant states.Here,we propose a novel implementation of this method based on the gradient optimization(CCR-GO).The main strength of the CCR-GO method is that it does not require manual adjustment of optimization parameters in the wave function;instead,a mathematically well-defined optimization path can be followed.Our method is proven to be very efficient in searching resonant positions and widths over a variety of few-body atomic systems,and can significantly improve the accuracy of the results.As a special case,the CCR-GO method is equally capable of dealing with bound-state problems with high accuracy,which is traditionally achieved through the usual extreme conditions of energy itself. 相似文献