Fig. 1. Solid-state laser for the generation of mode-switchable high-order CVB. L1, collimating lens; L2, L3, focus lenses; M, input mirror (HT@808 nm, HR@1064 nm); Nd:YAG, laser crystal; PBS, polarizing beam splitter; HWP, half-wave plate; VWP1 & VWP2: vortex wave plates; QWP1 & QWP2: quarter-wave plates; OC, output coupling mirror; P, polarizer; BQP, beam quality profiler.

Fig. 2. Profile and polarization states of a tunable high-order CVB generated by a microchip laser which goes through a round-trip path in the cavity. M, input mirror; PBS, polarizing beam splitter; HWP, half-wave plate; VWP1&VWP2, q-plates of order m = 1; QWP1 and QWP2, quarter-wave plates; OC, output coupling mirror.

Fig. 3. (a1)–(d1) Intensity distributions of the second-order CVBs generated using the group of first-order VWPs and intensity distributions after passing through a linear polarizer oriented at different angles of (a2)–(d2) 0; (a3)–(d3) π/4; (a4)–(d4) π/2.

Fig. 4. Stokes parameters and polarization azimuth of the second-order CVBs. (a1)–(d1) S₁, (a2)–(d2) S₂, (a3)–(d3) S₃, (a4)–(d4) PA.

Fig. 5. Intensity distributions of the Gaussian beam and the second-order CVB are generated (a1)–(a3) in the cavity and (b1)–(b3) outside the cavity, respectively, using the group of first-order VWPs; intensity distributions after passing through the linear polarizer placed at 0 (a4)–(a6) inside and (b4)–(b6) outside the cavity.

Fig. 6. (a) Output spectra. (b) Output power and pump power curves (the red is the Gaussian beam without VWP; the black and the blue are the Gaussian beam and second-order CVB with VWP).

Fig. 7. (a1)–(d1) Intensity distributions of the second- and fourth-order CVBs are generated using the group of first- and third-order VWPs; (a2)–(d2) measured intensity distributions after passing through a linear polarizer oriented at 0.

Fig. 8. (a1)–(h1) Intensity distributions of high-order CVBs are generated by different orders and numbers of VWP combinations inside the cavity; (a2)–(h2) measured intensity distributions after passing through a linear polarizer oriented at different angles of 0.