A full-spectrum numerical-dispersion compensation technique for the pseudospectral time-domain method

In the standard pseudospectral time-domain (PSTD) method, the approximation of temporal derivatives based on the central difference formula is only of second-order accuracy, which results in large numerical dispersion errors when the simulated structures are of electrically large size. In this letter, a numerical technique according to the principle of finite impulse response digital filtering is applied to reduce the errors by numerically modifying the material parameters, and therefore the updating equations, for the constitutive relations of arbitrarily materials. It is not only shown to be simple and stable, but also efficient in the reduction of numerical dispersion errors as demonstrated by the results obtained from both the theoretical derivation and the PSTD simulations of numerical examples.