Electrically‐Controlled Continuous Transformation of Vector Beams With Self‐Assembled Chiral Superstructures

ABSTRACT

Vector beam (VB) is characterized by spatially variant polarizations, and its polarization structure plays a critical role in distinct performances among applications like laser micro‐processing, optical tweezers, and super‐resolution imaging. Controllable transformation between different VB modes, such as radial/azimuthal polarization, will surpass fixed function and fit diverse scenarios; however, corresponding effective and convenient approach remains to be explored. Here, we propose and demonstrate the continuous VB transformation by electro‐thermally controlled uniformly self‐assembled chiral superstructures. The pseudo‐dielectric heating and the thermal responsivity of cholesteric liquid crystals are fully exploited to endow this delicate superstructure with an electro‐thermally tunable pitch, thereby yielding a controllable photonic band. By adjusting the alternating current signal, typically with a voltage ∼20.0 V and a frequency ∼18.0 MHz, the local polarizations are rotated in a synchronous and smooth manner, flexibly transforming the transmitted VB modes. The rotation angle is tuned continuously in a broad range exceeding 360°, corresponding to two full cycles around the equator of the higher‐order Poincaré sphere. The proposed method is also applicable to VBs with large topological charges. This work provides a practical solution for on‐demand VB manipulation, and might inaugurate multi‐functional modules in laser manufacturing, optical imaging, and metrology.