Vortex lattices with transverse-mode-locking states switching in a large-aperture off-axis-pumped solid-state laser

We report on optical vortex lattices (OVL) beams with phase-singularity arrays from a large-aperture diode-pumped Yb:CALGO laser. A distinct transverse-mode-locking (TML) effect is found in the OVL formation via controlling pump aperture and off-axis displacement. Various OVL patterns with vortex arrays can be generated in a TML state. While in a non-TML state, the emission is always a high-order Hermite–Gaussian or Ince–Gaussian mode. Interestingly, a stable TML can be started from a non-TML state by an intentionally induced perturbation. Based on the TML principle, a new closed-form expression is theoretically proposed for interpreting the transverse patterns and the evolution principle of various OVL modes, showing good agreement with the experimental results.