Fig. 1. Diagrams of the cross-section of radially polarized beam and azimuthally polarized beam

Fig. 2. Laser device diagrams using birefringence characteristics to select mode. (a) Nd∶YVO₄ mode selection^[11]; (b) two feedback modes for intracavity lenses^[20]; (c) diagram of the mold selection device that enables the joint action of c-cut crystal and axicon^[21]; (d) YVO₄ mode selection^[22]; (e) experimental device diagram for mode selection using thermally induced birefringence effect^[26]

Fig. 3. Laser device diagrams using polarized optical element selection mode. (a) Diagram of laser mode selection device with conical Brewster prism^[28]; (b) diagram of the axicon mirror laser mode selection device^[29]; (c) diagram of a dual-axis cone cavity selective laser mode device^[30]

Fig. 4. Photonic crystal grating mode selective laser^[33]. (a) Grating structure diagram (cross-section and top view); (b) experimental setup diagram

Fig. 5. Schematic diagrams of selecting mode by diffraction grating. (a) Schematic diagram of absorption grating and leakage grating^[36]; (b) the wavelength dependence of diffraction grating reflectivity under TM and TE polarizations, the experimental device diagram and the beam intensity distribution when the output power is 338 W, 568 W, 760 W, and 968 W^[39]

Fig. 6. Schematic diagrams of polarization shaping using a spatial phase retarder. (a) The polarization shaping diagram for a combined half-wave plate^[13]; (b) the experimental device, the structure diagram of the combined half-wave plate, and the measured spot distribution diagram^[41]; (c) schematic diagram of the experimental setup for generating radially polarized beam with a segmented helical retarder and a schematic diagram of the retarder^[44]; (d) schematic diagram of a nanograting^[46] and the experimental device diagram of the radially polarized laser amplifier using nanograting extra cavity polarization shaping^[50]

Fig. 7. Schematic diagrams of polarization shaping using liquid crystal devices. (a) The polarization shaping process of liquid crystal devices^[53]; (b) diagram of the experimental setup of a triangular common-path interferometer based on a single-phase SLM^[56]; (c) diagram of the Köster prism interference device based on a single-phase SLM^[58]; (d) schematic diagram of Q-wave plate polarization shaping^[59]

Fig. 8. Schematic diagrams of hollow optically pumped laser. (a) Experimental device diagram and beam intensity distribution^[62]; (b) schematic diagram of off-focus coupling to produce hollow beam, diagram of the experimental set-up, and distribution of radially polarized beam produced^[63]; (c) the principle diagram of hollow focusing lens converting hollow beam^[65]

Fig. 9. Schematic diagrams of radially polarized beam generated by interference superposition. (a) The experimental device of radially polarized beam generated by the superposition of Mach-Zehnder linearly polarized beam and circularly polarized beam^[14]; (b) schematic diagram of Sgnac interference device^[66]; (c) common path interferometer device diagram^[71]