On-chip optical twisted bilayer photonic crystal

TL;DR

This paper introduces twisted bilayer photonic crystals as a new platform for tunable optical properties, demonstrating their rich physics and potential for novel photonic applications through experimental visualization and theoretical analysis.

Contribution

It pioneers the concept of moiré engineering in nanophotonics by demonstrating twist-angle-tunable dispersion in bilayer photonic crystals, expanding the toolkit for optical property manipulation.

Findings

Optical dispersion is tunable via twist angle.

Measured optical response agrees with numerical and analytical models.

Twisted bilayer photonic crystals exhibit highly tunable band structures.

Abstract

Recently, moir\'e engineering has been extensively employed for creating and studying novel electronic materials in two dimensions. However, its application in nanophotonic systems has not been widely explored so far. Here, we demonstrate that twisted bilayer photonic crystals provide a new photonic platform with twist-angle-tunable optical dispersion. Compared to twisted two-dimensional materials, twisted bilayer photonic crystals host a rich set of physics and provide a much larger number of degrees of freedom choice of material, lattice symmetry, feature size, twist angle, and interlayer gap, which promises an unprecedented toolbox for tailoring optical properties. We directly visualize the dispersion throughout the optical frequency range and show that the measured optical response is in good quantitative agreement with numerical and analytical results. Our results reveal a highly tunable band structure of twisted bilayer photonic crystals due to moir\'e scattering. This work opens the door to exploring unconventional physics and novel applications in photonics.