Second-order accurate FDTD equations at dielectric interfaces

The rigorous second-order accurate finite-difference timedomain method equations at dielectric interfaces are straightforwardly derived though the discretization of the integral forms of Maxwell's curl equations on the nonuniform Yee's lattice and Taylor series extending of continuous field components over finite volumes including the interfaces. It is shown that to obtain second-order accuracy, we not only require to construct proper effective permittivities in the grids containing the dielectric interfaces, but also to choose nonuniform Yee's grids available in the vicinity of the interface.The attempts in the past are not appropriate for this purpose based on the uniform Yee's lattice. (C) 2007 Wiley Periodicals, Inc.