Light Confinement in Twisted Single-Layer 2D+ Moiré Photonic Crystals and Bilayer Moiré Photonic Crystals

Twisted photonic crystals are photonic analogs of twisted monolayer materials such as graphene and their optical property studies are still in their infancy. This paper reports optical properties of twisted single-layer 2D+ moire photonic crystals where there is a weak modulation in z direction, and bilayer moire-overlapping-moire photonic crystals. In weak-coupling bilayer moire-overlapping-moire photonic crystals, the light source is less localized with an increasing twist angle, similar to the results reported by the Harvard research group in References 37 and 38 on twisted bilayer photonic crystals, although there is a gradient pattern in the former case. In a strong-coupling case, however, the light source is tightly localized in AA-stacked region in bilayer PhCs with a large twist angle. For single-layer 2D+ moire photonic crystals, the light source in Ex polarization can be localized and forms resonance modes when the single-layer 2D+ moire photonic crystal is integrated on a glass substrate. This study leads to a potential application of 2D+ moire photonic crystal in future on-chip optoelectronic integration.