Dynamic Control of Intrinsic Optical Chirality through MEMS-Integrated Photonic Crystals

The active manipulation of intrinsic optical chirality in metamaterials paves the way for advanced polarization engineering, establishing a foundation for polarization-dependent, in-situ tunable sensing, imaging, and emission control. Despite recent progress in this field, challenges remain. In plasma-based chiral metamaterials, significant inherent losses hinder performance, whereas in dielectric systems, achieving intrinsic optical chirality (as opposed to extrinsic chirality) requires complex chiral geometries that present substantial fabrication challenges at the nanoscale. Moreover, achieving active tunability of intrinsic optical chirality is exceptionally challenging, as it demands angle-independent control over chiral resonances between the metamaterials and the incident light. To address these challenges, we present a novel metamaterial with actively tunable configurations capable of adjusting its geometrical chirality, realized through the integration of photonic crystal slabs and MEMS (micro-electromechanical systems). Here, we report the theoretical and experimental realization of dynamic control of intrinsic optical chirality in MEMS-integrated bilayer photonic crystals. The circular dichroism (CD) continuously varies from -0.85 to 0.64 in experiment and from -1 to 1 in simulation. Furthermore, we achieve precise manipulation of output polarization states through MEMS configuration control, offering a promising approach to realizing topologically protected unit CD within the parameter space across multiple frequencies. This study establishes a new pathway for overcoming the challenges associated with active, intrinsic optical chirality control, bringing us closer to practical applications in advanced polarization-dependent optical systems.