Finite element beam propagation method for anisotropic opticalwaveguides

A finite element beam propagation method (BPM) for anisotropic optical waveguides is newly formulated. In order to treat a wide-angle beam propagation, a Pade approximant operator is employed and to avoid nonphysical reflection from computational window edges, a transparent boundary condition is extended to anisotropic materials. To show the validity and usefulness of this approach, the numerical results for an anisotropic planar waveguide and a magnetooptic channel waveguide are presented     

A finite-difference vector beam propagation method forthree-dimensional waveguide structures

A finite-difference vector beam propagation method (FD-VBPM) for three-dimensional waveguide structures is developed. The polarization dependence and coupling of the optical guided-waves in the 3-D structures can be modeled and simulated     

有限元光束传输法分析锥形线性波导

文章介绍了有限元光束传输法(FE BPM)和完美匹配层法的结合,并用该法分析了不同折射率比和仰角的锥形线性波导,说明了这种方法的有效性和实用性.     

Simulation of waveguide birefringence by beam propagation method

It is demonstrated that, by modifying the waveguide geometry, the beam-propagation method (BPM) can be extended to determine the mode indexes of both polarizations. Such an approach has been implemented into BPM routines. It can be used to determine the birefringence in waveguide structures. The same approach is also applicable in other waveguide simulation programs based on the scalar field approximation. The operational principle and numerical results for planar waveguides are presented, and the extension of this technique to channel waveguides is discussed.<>     

Accurate finite difference beam propagation method for complexintegrated optical structures

A simple and effective finite-difference beam propagation method in a z-varying nonuniform mesh is developed. The accuracy and computation time for this method are compared with a standard finite-difference method for both the 3-D and 2-D versions     

基于有限差分光束传播法的过渡波导功耗分析

为了在既定尺寸下减小斜坡波导和弯曲波导的功耗，设计了4种过渡波导形状函数，用有限差分光束传播法(FD—BPM)进行了模拟分析，发现过渡波导形状的选取与坡度和曲折角存在条件关系，并给出了条件表达式和详细说明。     

光波导光束传输法数值分析新进展

介绍了用于光波导数值分析的光束传输法(BPM)的新进展,并对这些方法的优缺点、适用场合作了分析比较。     

用有限差分光束传输法分析过渡波导损耗

为了减小弯曲过渡波导和斜坡过渡波导的功耗,设计研究了几种过渡波导形状函数,并用有限差分光束传输法进行了模拟分析,发现过渡波导形状的选取与坡度和曲折角存在一定的条件关系,经总结给出了该条件关系表达式;并且,在分析计算不同形状过渡波导损耗的过程中,凸现出了有限差分光束传播法在光波导器件及其单元器件模拟分析中的直观性与方便性。     

A finite element beam propagation method for strongly guiding andlongitudinally varying optical waveguides

A unified finite element beam propagation method is described for both TE and TM waves propagating in strongly guiding and longitudinally varying optical waveguides with magnetooptic materials. In order to avoid nonphysical reflections from the computational window edges, the transparent boundary condition is introduced for both polarizations. In order to show the validity and usefulness of this approach, numerical examples are presented for a directional coupler composed of two parallel identical waveguides, an S-bend, a Y-branching optical isolator, and a 4-ports optical circulator. The present algorithm is, to our knowledge, the first beam propagation method for modeling nonreciprocal magnetooptic components     

Full-vectorial finite element beam propagation method withperfectly matched layers for anisotropic optical waveguides

Perfectly matched layer (PML) boundary conditions are incorporated into the full-vectorial beam propagation method (BPM) based on a finite element scheme for the three-dimensional (3-D) anisotropic optical waveguide analysis. In the present approach, edge elements based on linear-tangential and quadratic-normal vector basis functions are used for the transverse field components. To show the validity and usefulness of this approach, numerical examples are shown for Gaussian beam propagation in proton-exchanged LiNbO₃ optical waveguides. Numerical accuracy of the present PML boundary condition is investigated in detail by comparing the results with those of the conventional absorbing boundary condition (ABC)     

Study of form birefringence in waveguide devices using the semivectorial beam propagation method

Waveguide devices based on nonbirefringent substrates may still have form birefringence if index discontinuities exist. It is demonstrated that the semivectorial beam propagation method can be used to study the polarization dependence in waveguide devices. It is shown that the calculated coupling lengths of planar directional couplers match within 3.5% of analytical solutions. Results on polarization dependencies of coupling lengths and bending losses of rib waveguide devices are presented. Results of rib waveguide directional couplers indicate that the form birefringence can be significant. Losses of S-shaped bends are weakly polarization dependent in the low-loss regime.<>     

Combination of beam propagation method and mode expansionpropagation method for bidirectional optical beam propagation analysis

A combined method of the beam propagation method (BPM) and the mode expansion propagation method (MEPM) is proposed for the analysis of reflections of both transverse electric (TE) and transverse magnetic (TM) polarized waves in waveguiding structures containing longitudinal discontinuities. BPM based on the finite-element method (FEM) is applied to slowly varying regions and MEPM is applied only to regions including abrupt discontinuities. FEM is also utilized for evaluating the eigenmodes necessary for the MEPM analysis. To show the validity and usefulness of the present approach, numerical examples for a semiconductor laser facet with antireflection coating and an optical directional coupler are presented     

A wide-angle finite element beam propagation method with perfectlymatched layers for nonlinear optical waveguides

A beam propagation method (BPM) based on the finite element method (FEM) is described for the analysis of both transverse electric (TE) and transverse magnetic (TM) waves propagating in nonlinear optical waveguides. A perfectly matched layer is introduced to avoid spurious reflections from computational window edges. For the wide-angle beam propagation analysis, the Pade approximation is introduced to the differential operator along the propagation direction. In order to improve numerical accuracy and efficiency, a finite element mesh and a reference refractive index are adaptively renewed at each propagation step, and to reduce computational effort for the nonlinear optical waveguide analysis, an iterative algorithm is also introduced. Waveguides with nonlinear self-focusing claddings are analyzed to investigate spatial soliton emission phenomena, and it is confirmed that soliton couplers can be easily constructed     

Bidirectional beam propagation method

The formalism of the beam propagation method (BPM) is extended in a self-consistent way so as to allow the analysis of reflections in waveguiding structures containing longitudinal discontinuities     

Explicit finite difference beam propagation method: application to semiconductor rib waveguide Y-junction analysis

A novel explicit finite difference beam propagation method is developed and applied to the analysis of a strongly guiding semiconductor rib waveguide Y-junction. Its accuracy is confirmed by comparison with reported results. This method is much more efficient than the standard beam propagation method for the rib waveguide analysis.<>     

Finite element simulation for laser-induced SAW propagation in tooth

Laser ultrasonic technology, a noncontact nondestructive evaluation method, can be applied to evaluating the properties of human teeth. With a finite element method, this paper studies laser induced surface acoustic wave (LSAW) characteristics propagating in human teeth. Setting up a theory model for laser-introduced surface acoustic wave (SAW) propagating in human incisors, it discusses the temperature field induced by laser irradiate in dental surface, as well as the effects of inhomogeneous enamel and early dental caries (white spot lesion) on LSAWs. Studies in this letter can provide a theoretical basis for nondestructive evaluation of human teeth with laser ultrasonic technology.     

Finite element method using port truncation by perfectly matchedlayer boundary conditions for optical waveguide discontinuity problems

A powerful algorithm based on a finite element method (FEM) is newly formulated for the analysis of waveguide discontinuities. In an earlier approach, FEM was applied to the finite region with discontinuities, and a mode expansion technique was applied to the uniform waveguides that are connected to the input and output ports of finite region. Although, in the present approach, the uniform waveguides are replaced by perfectly matched layer (PML) boundary conditions, it is possible to treat periodically varying waveguide structures such as photonic crystal (PC) waveguides. A combined method of beam propagation method (BPM) and FEM is also shown in such a form that a mode expansion technique is not required. To show the validity and usefulness of the present approach, numerical examples for optical gratings, circuit components based on PC waveguides and optical directional couplers are presented     

Finite element method of lines analysis of open, periodic structures

The applicability of the finite element method of lines to the analysis of open, periodic structures is demonstrated. To validate the method and study its characteristics, the problem of transverse electric (TE) plane wave scattering from a metallic waveguide array is considered. Convergence of the solution is investigated both as a function of the mesh density and the order of the polynomial approximation used in the construction of basis functions.<>     

Finite element method analysis of discontinuities of multi-dielectric rods embedded in a parallel-plate waveguide

We have analysed various discontinuities inside a parallel-plate waveguide embedded with multi-dielectric rods by using an eight-node, isoparametric finite element method (FEM). The proposed FEM technique is very efficient and requires only small amounts of computer memory and computation time. In order to investigate the reflection and transmission properties of the structures, we have constructed diverse discontinuity configurations by choosing one, two or four dielectric rods inside a parallel-plate waveguide. The research results indicate that both the reflection and transmission coefficients of the structures are highly dependent on the geometrical dimensions, namely the height of the dielectric rods, the slot size of the slotted rods, as well as the total number of the dielectric rods.