Observation of a localized flat-band state in a photonic Lieb lattice

TL;DR

This paper experimentally demonstrates the excitation and robustness of a flat-band state in a photonic Lieb lattice, revealing its non-diffracting nature and insensitivity to disorder.

Contribution

It introduces a method to excite and analyze flat-band states in a photonic lattice, highlighting their robustness and potential for controlling light.

Findings

Flat-band states can be selectively excited in a photonic Lieb lattice.

These states exhibit non-diffracting behavior and are robust against disorder.

Experimental and theoretical analysis confirms the flat band's properties.

Abstract

We show experimentally how a non-diffracting state can be excited in a photonic Lieb lattice. This lattice supports three energy bands, including a perfectly flat middle band, which corresponds to an infinite effective mass with zero dispersion. We show that a suitable optical input state can be prepared so as to only excite the flat band. We analyse, both experimentally and theoretically, the evolution of such photonic flat-band states, and show their remarkable robustness, even in the presence of disorder.