Continuously Modulated Helical Dichroism of Tunable Chiral System by Magnetic Field Control

Dynamically tunable circular dichroism (CD) shows significant potential in biosensing, information storage and encryption, and optical displays. However, as another dimension of chiroptical responses, continuously tunable orbital angular momentum (OAM)-dependent helical dichroism (HD) spectra remain challenging. Here, we introduce a magnetically actuated tunable chiral system, which can realize geometric reconfiguration and the modulation of corresponding HD spectra under the control of a magnetic field. The geometric reconfiguration demonstrates fast responsiveness (∼2.01 s), stability, and robustness under magnetic actuation. The tunability and continuity of geometric chirality are demonstrated through Osipov–Pickup–Dunmur (OPD)-based simulations. Moreover, precise modulation of the OPD magnitude and peak position can be realized by adjusting various structural parameters. Continuous control of the OAM-associated HD spectra can be achieved with tunability ranging from −75% to 74%. This modulation of HD, attributed to the influence of the magnetic field, showcases the potential of this magnetically actuated flexible chiral system as a versatile platform for manipulating OAM beams, paving the way for chiral optical systems and dynamic beam shaping applications.