Revealing the Orbital Angular Momentum Spectrum and Correlation Phase of Optical Vortices With Wander Perturbations and Spiral Offsets

Controlling the orbital angular momentum (OAM) spectrum, as well as the modulus and phase of the first-order correlation function of a vortex beam produced by a dynamic wander source, is critical for the use of OAM photons in turbulent environments. Based on a derived analytical formula for the first-order correlation function of the light field, a theoretical model and an experimental approach are proposed for synthesizing and detecting complex wander vortex beams in the laboratory. Wander perturbations and spiral phase offsets are considered. The correlation phase and OAM spectrum of complex wander vortex beams are measured with a single spatial light modulator (SLM). The experimental results agree with the theoretical simulations and show that, given a limited region of interest, wander perturbations broaden the OAM spectrum asymmetrically with respect to the initial input mode, with a higher proportion of lower ordered non-signal modes than higher ordered modes. For a large spiral phase offset, the main peak of the OAM spectrum shifts away from the signal mode and toward a lower ordered side mode. Generation and measurement strategies have significant potential for free-space communication and remote sensing in turbulent environments.