Ultrafast tuning of tightly focused vector spatiotemporal optical vortices

Vector spatiotemporal optical vortices (V-STOVs), which combine spatiotemporal wave packet with a vector polarization structure, have attracted significant attention due to their unique physical property, structural diversity, and potential applications in ultrafast optics. In the tightly focusing regime, spatiotemporal optical vortices (STOVs) are expected to exploit novel properties through spatiotemporal coupling. However, it remains a challenge to achieve a stable and tunable focal field of STOV in a high numerical aperture (NA) system. Here, a new tightly focusing method based on V-STOV encoding is proposed, and the synergistic tuning of pulse width, vector polarization, and vortex order on the STOV focal field is achieved to our knowledge. It is uncovered that the polarization spatial structure of V-STOV plays a pivotal role in determining the rich and exotic features of the focal field. Interestingly, thenquantitative evaluation result reveals that the focal field distortion of V-STOV is smaller than scalar STOV (S-STOV), which is attributed to its spatiotemporal coupling characteristics. In addition, it is found that both the intensity and the transverse orbital angular momentum (OAM) distributions of the STOV exhibit a periodic evolution over time. The periodicity remains unchanged even during ultrafast pulse compression. This work may provide a new avenue for ultrafast spatiotemporal tuning of light, with potential applications in high-resolution imaging, particle manipulation, and laser material processing.