wgma

wgma is a library for analysis of optical waveguides using the NeoPZ C++ library.

notice: currently, wgma must be linked against the develop version of NeoPZ.

Along with the library, a few examples available in this repository illustrate the functionalities and capabilities of the library.

For the modal analysis of waveguides, all examples are based on a FEM formulation using a HCurl-conforming (H1-conforming) approximation space for the transverse (longitudinal) field components.

For the scattering analysis of planar waveguides, the implementation follows from Tsuji,Koshiba, 2002.

The wgma library is currently organised in the following namespaces

• wganalysis : namespace for modal analysis of waveguides. Contains the Wgma2D class for managing the modal analysis of waveguides with 2D cross-section.
• gmeshtools: auxiliary routines for creating structured curved meshes, reading .msh files and directional h-refinement
• cmeshtools: auxiliary routines for dealing with computational meshes and PML
• bctype: enum class with commonly used electromagnetic boundary conditions
• pml: base class for PML types
• pml::cart: class for cartesian PMLs
• pml::cyl: class for cylindrical PMLs
• modetype: enum class for distinguishing between TE/TM modes in the analysis of planar waveguides
• slepc: a few handlers for solving the eigensystem using the EPS module of SLEPc (usage is optional)

requirements

• A C++ 17 compiler
• CMake 3.14.0+
• A NeoPZ install configured with MKL support (note: develop version)

optional

• SLEPc (tested with 3.15.2)
• gmsh (formats msh3 and msh4 are supported. tested only with msh4)

If the SLEPc solver is used, NeoPZ need not have been configured with MKL. In order to use this package with SLEPc, one must configure both PETSc and SLEPc with complex scalar types.

Note: not all SLEPc configurations are available. PRs are welcome.

The following is merely a suggestion on how to configure these libraries:

PETSc

./configure --with-scalar-type=complex --with-debugging=0 
  --with-blaslapack-dir=$MKL_ROOT_DIR 
  --with-mpi-dir=$MPI_ROOT_DIR 
  --download-scalapack=yes --download-mumps=yes

SLEPc

./configure  --with-arpack=1 --with-arpack-dir=$ARPACK_BUILD_DIR
  --with-arpack-lib="-L$MKL_LIB_DIR -larpack -lparpack 
  -lmkl_gf_lp64 -lmkl_gnu_thread" --with-feast=0

available examples

wr90

Analysis of the WR90 waveguide.

Illustrates

• how to use the wgma library
• how to generate simple meshes in NeoPZ
• how to use the TPZKrylovSolver

stepfiber

Analysis of a step-index optical fiber.

Illustrates

• usage of cylindrical PML
• usage of the wgma::slepc::EPSHandler for using SLEPc solvers
• usage of non-linear mapped elements for representing curved geometries

ribwg

Analysis of a rib waveguide.

Illustrates

• reading a .msh file from gmsh
• directional refinement (useful for singularities)

ecf

Analysis of an Exposed-Core-Fiber

Illustrates

• performance in a real-world scenario
• how to generate dispersion curves and export to .csv

planar_wg

Scattering analysis of a planar slab waveguide with a discontinuity

Illustrates

• how to analyse 2D planar waveguides for a given excitation source
• how to analyse 2D planar waveguide discontinuities using port truncation with PMLs
• how to prescribe custom sources

pcwg

Modal analysis of a 2D photonic crystal followed by scattering analysis

Illustrates

• how to easily generate .msh meshes in python allowing for exact representation of curved geometries
• how PMLs can be set up for periodic domains
• how to perform more complex analysis and transfer the solution between different problems

slab_disc

Modal analysis of a slab waveguide followed by scattering analysis in a small region containing a waveguide discontinuity. Then, the scattered solution is projected onto the modes of the second section of the waveguide.

Illustrates

• how to integrate a given FEM solution (for orthogonalising modes for instance)
• how to insert probes in the mesh for visualising the solution
• how to deal with problems of dimension d-1 : identifying PML regions, etc

sf3d

Modal analysis of a step index optical fiber followed by a frequency analysis of the propagation of the dominant mode.

Illustrates

• how to solve large scale 3d problems using iterative solvers