AUTHOR=Lin Shibing , Wang Deen , Zheng Yamin , Guo Liquan , Zhang Yifan , Zhuang Yongchen , Huang Lei 

TITLE=Helicity and topological charge tunable optical vortex based on a Hermite-Gaussian beam dynamically controlled folded-cavity resonator

JOURNAL=Frontiers in Physics

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1192257

DOI=10.3389/fphy.2023.1192257

ISSN=2296-424X

ABSTRACT=Helicity and topological charge are two important characteristic parameters to the application of vortex beam, including optical communications, optical manipulation and material processing, etc. In this work, a helicity and topological charge tunable vortex laser based on a folded resonant cavity is presented. In the resonant cavity, a Z-shaped structure is adopted and two deformable mirrors (DMs) are cascaded into the cavity as intro-cavity modulation elements. By applying different voltage combinations to the DMs, the Hermite-Gaussian (HG) beam with different indices and distribution orientations θ could be generated from the Z-shaped folded-cavity resonator. The vortex beam with tunable helicity and topological charge is realized by using an extra-cavity astigmatic mode converter to transform the generated HG beam, and the simulation results verified the feasibility of the presented vortex laser. In the experiment, the HG_(m,0)^θ beam (m=1 to 10 and θ =-90° to 90°]) and the vortex beam (topological charge l from ±1 to ±10 and left/right helicity) were flexibly achieved through numerically adjusting the driving voltage combinations of the intra-cavity cascaded DMs.