title: Improving accuracy by subpixel smoothing in the finite-difference time domain.
abstract: Finite-difference time-domain (FDTD) methods suffer from reduced accuracy when modeling discontinuous dielectric materials, due to the inhererent discretization (pixelization). We show that accuracy can be significantly improved by using a subpixel smoothing of the dielectric function, but only if the smoothing scheme is properly designed. We develop such a scheme based on a simple criterion taken from perturbation theory and compare it with other published FDTD smoothing methods. In addition to consistently achieving the smallest errors, our scheme is the only one that attains quadratic convergence with resolution for arbitrarily sloped interfaces. Finally, we discuss additional difficulties that arise for sharp dielectric corners.
authors.affiliation: Center for Materials Science and Engineering and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. ardfar@mit.edu
authors.forename: A
authors.initials: A
authors.lastname: Farjadpour
authors.forename: David
authors.initials: D
authors.lastname: Roundy
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rodriguez
authors.forename: M
authors.initials: M
authors.lastname: Ibanescu
authors.forename: Peter
authors.initials: P
authors.lastname: Bermel
authors.forename: J D
authors.initials: JD
authors.lastname: Joannopoulos
authors.forename: Steven G
authors.initials: SG
authors.lastname: Johnson
authors.forename: G W
authors.initials: GW
authors.lastname: Burr