Fig. 1. DSS of OAM beam versus propagation distance

Fig. 2. Evolutionary propagation of wave source frequency doubling light and topological charge detection. (a) OAM wave source (fundamental frequency light); (b) propagation and evolution of transverse structure of frequency doubling light; (c) detection results of topological charges by inclined lens method

Fig. 3. Experimental setup

Fig. 4. Experimental results of transverse distribution and topological charge measurement of OAM frequency doubling beams. (a) Spot distributions of propagation evolution of frequency doubling beams with ?=4、8、16; (b) corresponding detection results of topological charges

Fig. 5. Frequency doubling power versus topological charge of OAM beam