Coupling condition analysis of Bessel–Gaussian beam to few mode fibers

In this paper, the theoretical model of the coupling efficiency of BG beams to few-mode fibers (FMFs) in the case of perfect alignment, lateral or vertical offsets, and random angular jitter is investigated and compared with that of sew-mode fibers (SMFs). Under the same conditions, FMF obtains a higher coupling efficiency with the BG beam and flatter response characteristics to deviations from ideal conditions compared with SMF. At the same time, the effects of the half-cone angle and topological charge of the BG beam on the coupling efficiency and response characteristics during nonideal conditions are studied. According to the precision of the coupling system, a higher coupling efficiency can be obtained by adjusting the half-cone angle, topological charge, and focal length. That makes them a more practical choice for information transmissions, such as mobile platform communication and the transmission of pedestrian data collected during transportation. The research results could help apply the BG beam and other orbital angular momentum (OAM) beams coupled with FMF.