A BEAM-PROPAGATION METHOD THAT HANDLES REFLECTIONS

We review the fast Fourier transform beam propagation method (FFT-BPM) that is commonly used to describe diffraction of electromagnetic waves and introduce a time-domain version that takes into account arbitrary longitudinal index profiles, as well as transverse effects. This method can describe all relevant aspects of paraxial propagation in linear or nonlinear media. That is, the technique can handle transmission, diffraction, and, in particular, reflection of electromagnetic waves.