Mechanical Tuning of Intrinsic Chirality in a Bilayer Electromagnetic Metamaterial via Out-of-Plane Rotation

Mechanically tunable chiral metamaterials provide an effective platform for reconfigurable polarization control of electromagnetic waves. Here, we propose a bilayer electromagnetic metamaterial with intrinsic chirality in its undeformed state. Under mechanical stretching, out-of-plane rotation of the resonators enables continuous suppression of circular dichroism (CD). This mechanical rotation reconfigures the relative alignment of effective electric and magnetic dipoles, thereby progressively weakening the chiral coupling. Experimental and numerical results confirm reversible CD modulation across two resonant modes, with a tunable range from -0.77 to near zero. Furthermore, under oblique incidence, the combined effect of the incident angle and mechanical rotation allows enhanced control over polarization azimuth rotation and ellipticity. This work offers a mechanically reconfigurable route for modulating intrinsic chirality in bilayer electromagnetic metamaterials and expands the design space for tunable chiral electromagnetic devices.