Theoretical and Experimental Research on the Mode Modulation Regulation for the Mode-Tunable Vortex Laser Based on Mode Conversion and Intra-Cavity Modulation

The vortex laser beam has been widely applied in many fields for its unique properties. However, researchers have to conduct extensive and recurring experiments to find the modulation abilities of the vortex beam modes for a given resonant cavity. In this paper, a mode modulation regulation acquisition (MORA) method, investigating the relationship between the modes of the vortex beam and modulation parameters, is proposed and verified. A typical mode-tunable vortex laser, consisting of a classic piano-concave straight cavity, a vortex beam generation beamline, and a reference beam acquisition beamline, is used as the analysis and experiment object. The principle and working process of the MORA method is analyzed in the simulation, and its validity is verified in the experiment. Based on the obtained theoretical relationship between the modes of the vortex beam and modulation parameters, the MORA method could be used to help researchers in designing the practical vortex laser with target vortex beams output by optimizing the structure of the vortex laser, selecting the suitable intra-cavity modulation elements (IMEs), and pre-positioning the location of the IMEs.