The nonorthogonal finite integration technique applied to 2D- and 3D-eigenvalue problems

Recently we proposed an advanced implementation of the FDTD algorithm on nonorthogonal grids, It was successfully included in the matrix-vector notation of the finite integration technique (FIT), and an interpolation formula was found, which ensures the long-term stability of the time integration. In this paper we propose the application of the nonorthogonal FI-technique (NFIT) to eigenvalue problems in the frequency domain, including both resonator and waveguide problems, Due to some modifications in the formulation of the eigenvalue problems the inversion of the material matrices can be avoided.