Wide angle beam propagation using oblique coordinates transformation

We propose a new wide-angle beam propagation algorithm based on an oblique coordinate transformation which extends the range of angled configurations for which beam propagation methods are accurate. This offers an extra degree of freedom within configuration and method when applying BPM´s in the design of general photonic integrated circuits incorporating angled waveguide sections. The present oblique wide angle propagation technique is compared with the conventional wide angle BPM through numerical examples which are a tilted propagation in a dielectric waveguide and the diffraction of a focused Gaussian beam in a homogeneous medium