Finite element modeling of wavelength-scale diffractive elements

Bernd Lichtenberg, Purdue University


The finite element method is used to model the near field of wavelength scale diffractive elements. Because open region problems are considered, local conformable radiation boundary conditions are implemented to truncate the domain. An analytical as well as a numerical comparison is used to evaluate boundary condition variants. Several implementation issues like mesh creation, solution methods for the resulting system of linear equations (direct solvers versus different conjugate gradient type iterative solvers coupled with preconditioning), solution visualization, as well as far-field parameter extraction like bi- and monostatic radar cross sections are addressed. Finally, results of modeling diffractive surfaces like gratings and Fresnel Zone Plates are presented. The design of a fast Fresnel Zone Plate is used to illustrate the use of the program to design and optimize such a diffractive element.




Gallagher, Purdue University.

Subject Area

Electrical engineering|Optics

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