Finite element approach for the modal analysis of open-boundarywaveguides

A general finite element approach to computing the modes of open-boundary waveguides is presented. This efficient and robust scheme applies equally to situations with real and complex propagation constants. By using a localised boundary impedance condition, the approach preserves the sparsity of the global matrices. A comparison with the well established infinite element technique and the analysis of a 2-D leaky optical structure are given as examples     

Improved all-optical switching in a three-slab nonlineardirectional coupler with gain

We propose and study numerically with a split-step finite-element method, an all-optical switching device made of three nonlinear active optical planar waveguides. Solving directly the nonlinear partial differential equations for the transverse electric polarised fields, the method can analyze real slab structures, where the gain is introduced by doping the guiding region with high erbium concentration. The effect of different amount of gain and loss on the switching performance is investigated. The introduction of suitable gain overcomes the problem of performance degradation due to losses, decreases the switching power and allows the input power to be successfully switched, by a simple power control, among all the three output ports     

Simple nonparaxial beam-propagation method for integrated optics

A simple beam-propagation method for solving the scalar TE nonparaxial or Helmoltz equation is presented. This versatile algorithm, based on a two-step finite-difference scheme for solving the propagation coordinate, is amenable to be easily extended to solve vector wave equations, which could take into account nonlinear effects. In addition, a general procedure to check its stability is given in detail. The applicability of the present method and its distinction from paraxial or Fresnel solutions are demonstrated through several examples, including very strongly guided structures of variable transverse section     

Novel FEM Approach for the Analysis of Cylindrically Symmetric Photonic Devices

A novel scheme based on a 2-D finite element method (2-D-FEM) for the frequency domain, in cylindrical coordinates in conjunction with the perfectly matched layers (PML), is proposed and validated here. This scheme permits the analysis and simulation of photonic devices, including discontinuities along the propagation direction. Also, the present approach takes into account the dispersive nature of metals at optical wavelengths.     

Time-domain full-band method using orthogonal edge basis functions

A new time-domain numerical approach for two-dimensional vectorial wave equation solutions based on slow wave variation is presented. The algorithm incorporates finite-element discretization and uses orthogonal edge basis functions to describe pulse propagation in optical waveguides.     

Genetic algorithm and finite-element design of short single-section passive polarization converter

A very short passive polarization rotator is proposed, consisting of a single-section asymmetric waveguide. The use of a genetic algorithm together with the finite-element method was crucial to achieve a structure with 99% polarization conversion and a length of 90 /spl mu/m. This optimum structure exhibits a low total insertion loss: 1.16 dB.     

Novel time-domain step-by-step scheme for integrated opticalapplications

A novel time-domain scheme, based on the slow-wave variation approach and computation of the second time derivative for the scalar two-dimensional wave equation, is presented. This scheme permits the simulation of problems involving very wide bandwidth spectra and allows one to use coarser spatial meshes and larger time steps than other reported approaches     

Novel finite-element formulation for vectorial beam propagationanalysis in anisotropic medium

A novel full-vectorial finite-element beam propagation method for dielectric anisotropic media is presented. This computationally efficient approach uses only the transverse magnetic field components and is free of spurious solutions. Comparisons with other numerical and experimental results validate the method     

Novel boundary condition for the finite-element solution ofarbitrary planar junctions

A novel boundary condition for a two-dimensional finite-element method (2D-FEM) is developed to simulate accessing waveguides to planar optical junctions. This new boundary condition is based on a paraxial approximation to the field's derivatives over the junction's ports. The formulation is very easily adapted within the 2D-FEM framework while providing good simulation results. Two examples are provided to show the applicability and reliability of the present method: a waveguide step discontinuity and a sharp waveguide bend