Engineering of energy band and its impact on light transmission in non-reciprocal Hermitian hourglass lattice

TL;DR

This paper explores a non-reciprocal Hermitian hourglass photonic lattice, demonstrating its ability to control energy bands, produce flat bands, and support edge states, thereby advancing energy band engineering in photonic systems.

Contribution

It introduces a novel non-reciprocal Hermitian hourglass lattice with multiple functionalities, including energy band inversion and edge state manipulation, expanding the understanding of photonic band regulation.

Findings

Achieved energy isolation effect in the lattice

Demonstrated flat bands with localized states

Observed double edge states with defects

Abstract

We study a quasi-one-dimensional non-reciprocal Hermitian hourglass photonic lattice that can accomplish multiple functions. Under the effect of non-reciprocal coupling, this lattice can produce an energy isolation effect, two kinds of flat bands, and energy band inversion. The excitation and propagation of a single energy band and multiple energy bands can be realized; in the flat band condition, the system has compact localized states, and the flat bands can be excited by a straightforward method. In addition, we investigate the edge states under the open boundary condition; a double edge state appears by using a defect in the system. Our findings advance the theory of energy band regulation in artificial photonic lattices.