Method Based on Fast Fourier Transform for Calculating Conical Refraction of Beams With Noncircular Symmetry

Conical refraction of optical beams with circular symmetry is often analyzed using Belsky–Khapalyuk–Berry (BKB) theory; however, for beams with noncircular symmetry, it is difficult to obtain analytical expressions for far-field diffraction patterns. We propose a method, based on fast Fourier transform (FFT), for calculating conical refraction of beams with noncircular symmetry and verify it experimentally using a quasi-plane wave passing through a square aperture and focusing lens. Excellent agreement between theoretical and experimental results has been achieved.