Generation of a large orbital angular momentum beam via an optical fiber winding around a curved path and its application* *Project supported by the National Natural Science Foundation of China (Grant No. 11504074) and the State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University (Grant No. KF202004).

Abstract

Many papers have been published on the study of orbital angular momentum (OAM) of the laser modes based on the Laguerre–Gaussian (LG) beam and helical phase plate or rotating cylindrical lens, and the principal ray of the LG beam remains straight line. These ways are difficult to get a large OAM modes. In this paper, we propose a novel method to prepare a large OAM modes when the light propagates through a optical fiber winding around a curved path, and establish a theoretical framework based on the principal ray path changing. Firstly, we investigate three kinds of winding structure. Secondly, based on the analytical solutions and numerical calculations, we can find that the spiral body can achieve a large OAM temporal pulse. At the same time, based on the zero OAM diffraction diagram, we can obtain an improvement of resolving power beyond Rayleigh’s criterion. Finally, applying a large OAM diffraction pattern to realize 12-bitencodes, we can obtain a high-security optical information transfer system.