Generation of Spiral Interference Fringes with Few Mode Optical Fibers

Abstract

We demonstrate a method to generate spiral interference fringes with a few-mode optical fiber. These are generated from the interference of donut shaped vector vortex modes of few mode fiber with a Gaussian plane wave. These spiral fringes are the consequence of helical wave fronts of the donut shaped vector vortex modes, originating from the skew ray propagation of electromagnetic radiation within the fiber core.