Multi-degree-of-freedom radially self-accelerating beams via angular-spectrum engineering

Radially self-accelerating beams (RSABs), owing to their rotating propagation and orbital angular momentum (OAM) properties, have found applications in optical micromanipulation and optical metrology. However, conventional RSABs exhibit fixed propagation behaviors, and existing shaping approaches often lack compatibility, restricting their applicability in complex real-world scenarios. In this work, we propose an angular-spectrum engineering approach based on Fourier optics, enabling the design and control of multi-degree-of-freedom RSABs (Multi-DoF RSABs) with programmable angular velocity, longitudinal intensity, three-dimensional trajectory, and OAM. Experimental results demonstrate independent adjustment of these four degrees of freedom, in agreement with theoretical predictions. This work provides a flexible framework for designing RSABs and highlights their potential for applications in optical manipulation and microfabrication.