Real‐Time Observation of Breathing Vortex Solitons in a Yb:CALGO Laser

Abstract A direct induction method for breathing vortex solitons in an ultrafast vortex laser oscillator is proposed and experimentally validated in this study through the establishment of a dynamic gain‐loss regulation mechanism. The oscillator architecture employs a semiconductor saturable absorber mirror assisted Kerr lens mode‐locking technique for longitudinal mode phase locking and a spot‐defect mirror for transverse mode modulation. Following precise calibration to align the defect center of the spot‐defect mirror with the cavity axis, the system successfully generates stable ultrafast vortex beams. Building on this stationary ultrafast vortex beam output, a gain–loss dynamic regulation mechanism is established through coordinated adjustment of the plano‐concave mirror separation and pump power parameters, thereby driving the system toward the stability boundary. Experimental characterization reveals that the vortex beam acquires additional modulation frequencies during this regulation process, providing definitive evidence for breathing vortex soliton excitation. Significantly, when the average output power decreases from 1.7 to 1.45 W, complex breathing states including double‐period oscillation modes and breathing vortex soliton molecular complexes are observed, extending beyond the fundamental single‐period breathing state. This work provides a novel experimental platform for investigating the complex dynamical behaviors of breathing vortex solitons.