Robust propagation of pin-like optical beam through atmospheric turbulence

We design and demonstrate what we called shape-preserving "optical pin beams" (OPBs) that possess stable wavefronts against diffraction and ambient turbulence during free-space long distance propagation. Theoretically, we show that a laser beam passing through properly assembled phase elements paired with opposite transverse wavevectors can morph quickly into a stable optical field, exhibiting "self-focusing" dynamics during propagation without optical nonlinearity. The overall shape of such OPBs remains invariant, while their width can in principle be inversely proportional to the propagation distance, in contradistinction to conventional Bessel beams and radially symmetric Airy beams. Experimentally, utilizing a single photoetched mask, we demonstrate efficient generation and robust propagation of the OPB through atmospheric turbulence beyond kilometer distances. We envisage exciting opportunities arising from such OPBs, especially when propagation through turbulent environments is unavoidable. (C) 2019 Author(s).