Novel optoelectronic phenomena in supertwisted electronic and photonic crystals

In recent years, studies of twisted moire systems have garnered intense interest across many research communities. When two layers with similar lattice structures are stacked with a slight misalignment, they form a moire superlattice with enlarged periodicity. This large length scale modulation dramatically alters the band structure, enabling the emergence of flat bands and small Brillouin zones. In twisted van der Waals materials, the kinetic energy of electrons is quenched and many-body interaction dominates their property leading to new quantum geometry effects and the discovery of new correlated phases. In photonics, twisted moire photonic crystals provide localized optical modes and tunable resonances leading to the observations of moire lasers, quasi-BICs that can have important implications for new types of photonic devices. However, many of the studies have been limited to only a few layer systems where the third dimension is often neglected. Here, we focus on 3D twistronics on a platform of self-assembled spiral superlattice of multilayered WS2. Our findings reveal an opto-twistronic Hall effect driven by both structural chirality and coherence length, modulated by the moiré potential of the spiral superlattice. We discover signatures of enhanced light-matter interactions and a strongly coupled photon momentum-lattice interaction that cannot be explained by existing theoretical models. Crucially, our findings uncover the role of higher-order quantum geometrical tensors in light-matter interactions, opening new avenues for designing quantum materials-based optoelectronic lattices with large nonlinearities. We will also discuss our recent theoretical and experimental effects to understand bilayer twisted photonic crystals where we properly account for both near- field coupling and far-field response, which leads to intriguing effects. The framework we established sets the stage for a broad range of future studies in moire photonic systems, offering a versatile platform for exploring light-matter interactions, engineered band structures, novel topological effects, and beyond.