Realization of all-band-flat photonic lattices

TL;DR

This paper demonstrates a method to realize all-band-flat photonic lattices of arbitrary size by precisely controlling coupling strengths, enabling complete flatband formation and advanced control over band structure and topology.

Contribution

The authors develop a novel approach to create all-band-flat photonic lattices of any size by engineering coupling strengths, surpassing traditional methods that only produce limited flatbands.

Findings

Successfully realized all-band-flat photonic lattices of arbitrary size.

Achieved simultaneous high flatness and large bandwidth in the lattices.

Demonstrated selective excitation of eigenmodes with different chiralities.

Abstract

Flatbands play an important role in correlated quantum matter and have novel applications in photonic lattices. Synthetic magnetic fields and destructive interference in lattices are traditionally used to obtain flatbands. However, such methods can only obtain a few flatbands with most bands remaining dispersive. Here we realize all-band-flat photonic lattices of an arbitrary size by precisely controlling the coupling strengths between lattice sites to mimic those in Fock-state lattices. This allows us to go beyond the perturbative regime of strain engineering and group all eigenmodes in flatbands, which simultaneously achieves high band flatness and large usable bandwidth. We map out the distribution of each flatband in the lattices and selectively excite the eigenmodes with different chiralities. Our method paves a new way in controlling band structure and topology of photonic lattices.