Correlation function of partially coherent vortex beams induces changes in the orbital angular momentum spectrum

The crosstalk of orbital angular momentum (OAM) modes induced by random light fields poses a significant challenge in free-space optical communication. Analyzing the influence of such fields on the OAM spectrum is therefore essential. Based on the coherence–orbital angular momentum (COAM) matrix, we derive analytical expressions for the OAM spectrum of partially coherent vortex beams (PCVBs) with three distinct correlation functions. Our results show that both the global coherence and the form of the correlation function significantly affect the OAM spectrum. We explain the underlying physical mechanism and support our findings with numerical simulations that closely align with the analytical predictions. This work advances the study of partially coherent light with tailored correlation structures.