Decoupled Spectral Tuning and Polarization Locking in Twisted α‐MoO 3 Polaritonic Crystals

ABSTRACT Polaritonic crystals (PoCs), formed by integrating periodic lattices with two‐dimensional polaritonic materials, provide a powerful platform for nanoscale light manipulation and far‐field spectral engineering. However, far‐field spectral engineering in existing PoCs is primarily achieved through geometric redesign, requiring structural reconfiguration to access different spectral responses. Here, we overcome this limitation by constructing a twisted bilayer ‐ PoC consisting of a patterned and a pristine layer, where interlayer twist enables spectral tuning without geometric modifications. Meanwhile, the principal crystal axis of the patterned layer deterministically governs the axes of polarization‐selective resonances arising from lattice‐assisted polariton excitation. This polarization‐locking behavior remains robust against interlayer twisting, enabling independent control over the spectral response and the polarization direction. These findings provide a deterministic strategy for constructing deep‐subwavelength PoCs for multidimensional infrared light manipulation, offering new opportunities for advanced flat optics and reconfigurable nanophotonic devices.