Mode-locked cylindrical vector vortex beam unlocked the generation of a 2 µm multidimensional ultrafast laser

The development of multidimensional lasers, particularly 2 µm vector vortex pulsed beams, has garnered significant interest for applications in laser medicine and optical communication. This paper reports the successful achievement of mode-locked azimuthally polarized vector beams (APVB) and radially polarized vector beams (RPVB) in a c-cut Tm:CaYAlO 4 crystal cavity. Utilizing a semiconductor saturable absorber mirror (SESAM), the laser produced output powers of 110 mW (APVB) and 98 mW (RPVB), with pulse durations of 41.2 ps and 49.7 ps, and vortex topological charges of -1 and +1, respectively. This represents the first stable mode-locked states of the cylindrical vector vortex beam in a 2 µm solid-state laser.