Slant incident plane wave introduced in 2D-FDTD for layered background

In FDTD calculation of layered media, it is difficulty to set the slant incident plane wave in arbitrary layered background media. To solve this problem, 1D Maxwell's equations including oblique incident angle are derived based on 2D equations for TM and TE modes,they are then used to simulate plane wave slanting along the connective boundaries in layered media. Computations aiming at the fused silica covered with thin film indicate the electromagnetic wave impels perfectly in each layer and validate the scheme for introducing plane wave. The computation of damaged component holding vacuum bubble is also given to illuminate the application．