Electromagnetic models for finite aperiodic diffractive optical elements (Q2758027)

The paper considers numerical electromagnetic models for finite aperiodic diffractive optical elements. Since feature sizes of modern micro-optical elements approaches the wavelength of illumination, scalar diffraction theory becomes invalid and a complete solution to the underlying electromagnetic boundary value problem must be used. Due to the large extent of these devices (compared with the wavelength) the finite-difference time-domain method (FDTD) has received by far the most interest within the engineering community. Its memory requirements are significantly lower than those of other methods, which makes it possible to analyse realistic devices in reasonable timeframes. The authors give an overview of recent progress in the application of the FDTD to two-dimensional, axially symmetric and full three-dimensional structures. They discuss numerical stability, dispersion problems, different absorbing boundary conditions and the modelling of the incident field. One serious limitation of FDTD is caused by the use of rectangular grids. The boundary element method (BEM) is one of the techniques to overcome this limitation. In the second part the authors describe the classical BEM for Helmholtz equations and a more realistic approach, which utilizes specific properties of diffractive optical elements to reduce computational and memory requirements.NEWLINENEWLINEFor the entire collection see [Zbl 0964.00050].