Fiber coupling of partially coherent Laguerre Gaussian vortex beam in a Cassegrain antenna system

Abstract In consideration of the importance of the partially coherent beam (PCB) in optical communication, the coupling of partially coherent Laguerre Gaussian vortex beam (PCLGVB) with single-mode fiber after passing through a Cassegrain transmitting antenna is researched. Meanwhile, the effect of atmospheric turbulence and the assembly misalignments is also considered. In the paper, the transmission of a PCLGVB through a Cassegrain transmitting antenna is mathematically modeled and the coupling efficiency is numerically calculated. And as the propagation distance increases, the coupling efficiency shows an upward trend. In the meanwhile, the PCB is more resistant to the disruptions introduced by atmospheric turbulence and misalignments. And for the coupling between PCLGVB and the single-mode fiber, as the lateral offset or tilt angle increases, the coupling efficiency remains stable in some intervals, or even appears to grow anomalously, which may provide a new idea for enhancing the coupling efficiency. Compared to the case of perfect alignment, the lateral offset of 0 with a tilt angle of 6.5° has a higher coupling efficiency of 21.35%.