Watt-Level Second-Order Topological Charge Ultrafast Green Vortex Laser with Quasi -2D PEA2(CsPbBr3)n-1PbBr4 Perovskite Films Saturable Absorber

Ultrafast vortex beams have significant scientific and practical value because of their unique phase properties in both the longitudinal and transverse modes, enabling multi-dimensional quantum control of light fields. Directly generating watt-level ultrafast vortex beams with large angular momentum has remained a major challenge due to the limitations of mode-locked materials and existing spatiotemporal mode-locking generation methods. In this study, quasi-2D PEA₂(CsPbBr₃)_n-1PbBr₄ perovskite films are prepared by an anti-solvent method and employed for the first time in a mode-locked resonator operating in free space. Utilizing the angle-based non-collinear pumping and frequency doubling techniques, the second-order ultrafast green vortex beams with a power of up to 1.05 W and a duration of 373 ps are generated. Experimental findings demonstrate the strong nonlinear saturable absorption properties of quasi-2D PEA₂(CsPbBr₃)_n-1PbBr₄ perovskite films at high power levels, highlighting their considerable potential in ultrafast laser technology and nonlinear optics.