This work presents the analysis of the Lorentz
light beam at a planar dielectric interface
using accelerated beam propagation method
(BPM). the FFT-BPM is implemented on a
graphical processing unit (GPU) platform
using CUDA-C program to decrease the
execution time significantly. In this study, the
interference between the incident and
reflected beams is reported. Additionally, the
angular spread of the refracted beam in the
rare medium and its direction of propagation
are considered. The non-specular shifts are
also calculated using the FFT-BPM at sharp
critical angle which is very difficult to
examine using analytical methods.