Dynamically twistable three-dimensional moiré photonic crystals

Abstract

Three-dimensional woodpile photonic crystals constitute one of the most successful architectures for realizing photonic band gaps, yet their optical response is traditionally fixed by the geometry established during fabrication. Here, we introduce a twist-controlled woodpile photonic crystal in which the relative angular orientation between successive rod layers acts as an additional, in situ-tunable geometrical degree of freedom. Using an extension of rigorous coupled-wave analysis adapted to multilayer structures with rotated reciprocal lattices, we systematically investigate the evolution of the transmission spectrum as a function of twist angle. We show that twisting drives the structure through three distinct photonic regimes. In the fully aligned configuration, broad frequency intervals exhibit near-unity transmission. At intermediate twist angles, the spectrum becomes populated by strongly dispersive resonances displaying characteristic Fano line shapes, high quality-factor and pronounced angular sensitivity. As the twist angle approaches 90°, the conventional woodpile structure is recovered, and these resonances evolve into a broad photonic stop band characteristic of three-dimensional photonic crystals. A simplified analytical model based on reciprocal-lattice considerations accurately reproduces the principal resonance modification observed in the numerical calculations. Our results demonstrate a continuous twist-induced transition from broadband transmission to photonic stop bands through an intermediate Fano-resonant regime, establishing twisted woodpiles as a versatile platform for three-dimensional twist-engineered photonics.