Work

Generation of spatiotemporal optical coil with controllable transverse intensity chirality

Year: 2026

Type: article

Abstract: Chirality is a fundamental asymmetry in nature. In optics, control of chirality is evolving from spatial properties like polarization to the temporal chirality of local fields. Conventional approaches, however, encode chirality in abstract degrees of freedom such as phase or polarization, limiting direct and efficient coupling with matter on ultrafast timescales. We introduce and experimentally demonstrate a paradigm of intensity-driven optical chirality, where handedness is physically inscribed into the trajectory of spatiotemporal energy flow. Through the engineered non-collinear collision of Spatiotemporal Optical Vortices, the spatiotemporal optical coil is generated. The coil's chirality manifests as a physical torsion of its volumetric energy flow, a property distinct from chirality hidden in phase or polarization. By employing femtosecond tomography and phase-resolved reconstruction, we map the complete three-dimensional spatiotemporal intensity field, directly observing the evolution of singularity lines. This approach reveals programmable scaling relations between the coil's topology and interaction geometry, extending the concept of chirality to the energy-flow level. The introduced volumetric chiral density directly correlates with the optical forces and torques exerted on chiral particles, providing an intensity-manifested degree of freedom for topological photonics and enabling novel schemes for ultrafast chiral-selective excitation and high-dimensional information encoding.

Source: Light Science & Applications

DOI: 10.1038/s41377-026-02432-0