Fig. 1. Experimental setup for vortex beam generated by defect-spot mirror and Mach-Zehnder interferometer

Fig. 2. Micrograph images of defect-spots. (a) 150 μm; (b) 200 μm; (c) 250 μm

Fig. 3. Spot patterns and interference patterns produced by defect-spots

Fig. 4. Simulation results of laser spot diameter

Fig. 5. Relationship between spot diameter and ellipticity of laser mode(fundamental mode) and cavity length. (a) Diameter; (b) ellipticity

Fig. 6. Optical-to-optical conversion efficiency of vortex beam versus cavity length under different defect-spot diameters. (a) 150 μm; (b) 200 μm

Fig. 7. Optical-to-optical conversion efficiency of vortex beam versus ellipticity of laser mode under different defect-spot diameters. (a) 150 μm; (b) 200 μm

Fig. 8. Optical-to-optical conversion efficiency of vortex beam versus diameter of laser mode under different defect-spot diameters. (a) 150 μm; (b) 200 μm

Fig. 9. Output power curves at maximum optical-to-optical conversion efficiency of vortex beam under different defect-spot diameters. (a) 150 μm; (b) 200 μm