Triple-order Orbital-angular-momentum modes generation based on single tilted fiber Bragg grating in a few-mode ring-core fiber

摘要

Orbital-angular-momentum (OAM) modes generation using tilted fiber Bragg grating (TFBG) in a few-mode ring-core fiber (FM-RCF) is proposed and demonstrated. Theoretical and experimental investigations reveal that OAM beams can be switched among three topological charges (+/- 1,+/- 2, and +/- 3) at different corresponding oscillation wavelengths by single TFBG. In this work, OAM beams with linear polarization are produced by combining four degenerated vector modes. We firstly use TFBG to directly generate OAM beams with three different topological charges in FM-RCF, which provides an increased stability and compatibility for the manipulation and control of the OAM beams states in optical fibers.