Temperature-Adaptive reconfigurable chiral metamaterial for tailoring circular dichroism based on shape memory alloy

Self-adaptable materials with autonomous morphological transformation by sensing environmental changes have emerged as one of the most promising but challenging approaches for various chiral devices. Unlike previous work on reconfigurable chirality through human intervention, we proposed a temperature-adaptive chiral meta-device. It can autonomously sense the environment and manipulate the optical chirality through 3D-to-3D morphological transformation. As a proof of concept, a 3D morphable chiral meta-device was designed with shape memory alloy (SMA), resulting in reconfigurable circular dichroism (CD). The curving direction of SMA enables the meta-device to switch between left-handed, right-handed, and non-chirality by sensing environmental temperature. The analysis of surface currents and CD spectra reveals that the underlying physical mechanism behind the chirality originates from the surge of toroidal and electric quadrupole dipole moments. Simultaneously, the spin-to-orbital angular momentum conversion is realized based on the Pancharatnam-Berry phase, where the topological charge is modulated by the environmental temperature. Encouragingly, this work paves the way for the self-adaptive chiral meta-devices with 3D morphological transformation and can be applied to a series of novel photon-spin-selective devices for optical communication and biosensing.