Low-loss twist-tunable in-plane anisotropic polaritonic crystals

• DOI: 10.48550/arxiv.2409.07861
• Publication Date: 2024-09-12
• Authors: Nathaniel Capote‐...; Ana I. F. Tresgue...; Aitana Tarazaga M...; Enrique Terán-García; L. Martı́n-Moreno; Pablo Jesús Alons...; Alexey Y. Nikitin
• Keywords: FOS: Physical sciences; Physics - Optics; Optics (physics.optics)

Van der Waals (vdW) materials supporting phonon polaritons (PhPs) - light coupled to lattice vibrations have gathered significant interest because of their intrinsic anisotropy and low losses. In particular, $\alpha$-MoO$_3$ supports PhPs with in-plane anisotropic propagation, which has been exploited tune the optical response twisted bilayers trilayers. Additionally, various studies explored realization polaritonic crystals (PCs) lattices periods comparable polariton wavelength -. PCs consisting hole arrays etched in slabs exhibit Bragg resonances dependent on angle between crystallographic axes vectors. However, such PC concept, a fixed orientation size its geometrical parameters, constrains practical applications introduces additional scattering losses due invasive fabrication processes. Here we demonstrate novel concept that overcomes these limitations, enabling low-loss tuning. It comprises rotatable pristine layer located periodic array fabricated metallic layer. Our design prevents degradation properties caused by fabrication, preserving propagation PhPs. The resulting exhibits rotation Bloch modes, is experimentally visualized scanning near-field microscopy. addition, determine momentum reconstruct band structure. These results pave way for mechanically tunable nanooptical components based potential lasing, sensing, or energy harvesting applications.