On-chip light trapping in bilayer moiré photonic crystal slabs

Abstract

The optical response of bilayer moiré photonic structures can be precisely controlled by varying the lattice geometry. Bilayer moiré photonic crystal slabs exhibit flat bands in the optical band structure, where the optical modes have zero group velocity. They also give rise to momentum-independent light-trapping of Bloch waves in both transverse and vertical directions, leading to high quality-factors (Q=109) and small mode volumes (V=0.12 λ2). The large Q and small V lead to a large Purcell enhancement (FP=1035), providing opportunities for low-threshold lasing, enhancement of optical nonlinearities, and quantum information processing.