Dynamic control of intrinsic optical chirality via MEMS-integrated photonic crystals

Chiral nanophotonic structures offer unprecedented design flexibility for enhancing chiral optical responses, yet dynamic tuning of such responses remains a key challenge. Here, we demonstrate intrinsic optical chirality tunability in reconfigurable bilayer photonic crystal slabs integrated with micro-electromechanical systems (MEMS). The chiral nature arises from strongly coupled dipole modes in the bilayer structure, whose optical characteristics are tuned via the interlayer gap and twist angle. We report measured intrinsic circular dichroism varying from −0.85 to 0.64. Our theoretical analysis reveals that this platform supports topologically protected states capable of reaching unit circular dichroism, establishing a robust pathway for arbitrary polarization control. This compact, all-dielectric device paves the way for applications in chiral sensing, dynamic polarization modulation, optical communications, and quantum photonics.