Synthesis of dynamic vector optical fields based on metasurfaces

Controlling the spatiotemporal evolution of light is crucial for exploring ultrafast light-matter interactions. Spatiotemporal optical field synthesis requires fine spatial resolution and a broad bandwidth. When the metasurface is placed on the focal plane of the Fourier transform system, with the help of the nanoscale multi-dimensional light control capability provided by the metasurface, parallel manipulation of each spectral component can be carried out over a wide frequency band, thereby achieving effective regulation of the spatiotemporal evolution of the beam. This advanced control mechanism facilitates the construction of complex spatiotemporal optical fields, including those featuring instantaneous polarization states changing at the femtosecond level. However, dynamically tunable vector optical fields with integrated spatiotemporal control are still neglected in existing studies. In this study, based on the spatiotemporal Fourier transform pulse synthesizer embedded with metasurfaces, we theoretically achieved dynamically tunable vector optical fields through independent dispersion control and angular momentum control of left-handed circular polarization and right-handed circular polarization. As a verification, we simulated and achieved the femtosecond-level dynamic conversion between radially and azimuthally polarized light in the near-infrared band and analyzed their spatiotemporal evolution characteristics. This method enables novel applications requiring coordinated spatiotemporal-polarization control, such as nanoparticle optical manipulation and multi-dimensional optical communication, with additional application prospects in laser plasma and optical topology.