Tailoring monolayer moiré-flatband superlattices through long-range lattice-site perturbations

We propose a direct approach for tailoring monolayer moiré superlattices, which is based on artificially designed long-range lattice-site perturbations. We show that this approach produces two distinct extreme sublattices within a supercell, leading to the emergence of staggered band structures associated with flatband formation. In the full-wave simulation with a square lattice, we clearly find a flatband emerging within the predicted spectral range, which has a mode profile localized at the predefined region. Besides, such a flatband resonance is found to exist persistently in a finite-size single-cell slab, while the supercell size is inherently scalable. Particularly, by increasing the supercell size from 7a to 9a, the quality factor of the moiré resonance rises dramatically from ∼0.67×10⁴ to ∼3.1×10⁴. Furthermore, as the far-field radiation profile is practically important, we introduce a new degree of freedom, i.e., the topological alignments of anisotropic scatterers, and demonstrate its effectiveness in shaping the far-field patterns. This work thus offers an attractive route toward high-performance moiré resonators, which is relevant to applications such as the development of micro lasers and nonlinear optical devices.