Optical catastrophes of the swallowtail and butterfly beams

Abstract

We experimentally realize higher-order catastrophic structures in light fields presenting solutions of the paraxial diffraction catastrophe integral. They are determined by potential functions whose singular mapping manifests as caustic hypersurfaces in control parameter space. By addressing different cross-sections in the higher-dimensional control parameter space, we embed swallowtail and butterfly catastrophes with varying caustic structures in the lower-dimensional transverse field distribution. We systematically analyze these caustics analytically and observe their field distributions experimentally in real and Fourier space. Their spectra can be described by polynomials or expressions with rational exponents capable to form a cusp.