Fig. 1. (a) Schematic diagram of CW Nd:YAG laser by using annular pumping, and (b) captured intensity distribution of pumping light at L4’s focal plane by applying 90 μm off-focus coupling.

Fig. 2. (a) Far- and (b) near-field intensity distributions of the laser beam at 3.2 W pump power for CW Nd:YAG laser; (c)–(f) far-field intensity profiles of laser beam transmitted through the polarizer analyzer. The white arrows indicate the respective orientations of the polarizer analyzer’s axis.

Fig. 3. (a) Experimental setup of Mach–Zehnder interferometer and spiral interference patterns with (b) right handedness and (c) left handedness at an incident pump power of 3.2 W. M1, M2, flat mirror with high reflectivity; L1, lens with f=40  mm.

Fig. 4. (a) Far- and (b) near-field intensity distributions of the laser beam at Pabs=3.8  W for passively Q-switched Nd:YAG laser; (c)–(f) variations of far-field intensity distribution of the passage beam through the polarizer analyzer with different orientations of the polarizer axes (where white arrows indict the directions of the polarizer analyzer’s axis); (g) measured interference pattern.

Fig. 5. (a) Far- and (b) near-field intensity distributions of the laser beam; (c)–(f) variations of far-field intensity distribution of the passage beam through the polarizer analyzer with different orientations of the polarizer axes (where white arrows indict the directions of the polarizer analyzer’s axis); (g) measured spiral interference pattern with left handedness.