What is it about?
Our work proposes a versatile method to create and manage flatbands in photonic systems that have a balance between gain and loss. We explore a lattice model formed by combining two systems that follow parity-time (PT) symmetry, resulting in the emergence of two flatbands. By adjusting the non-Hermiticity within this combined lattice, one can shift the flatbands from being completely flat to merging with the dispersive bands while still maintaining their flat nature, all thanks to the protection offered by the PT symmetry. When reaching a point called the exceptional point (EP), where the two flatbands merge into a single flatband, and go beyond it, one of the flatbands changes into a partial flatband. Simultaneously, the imaginary components of the band structure manifest as multiple flatbands. Furthermore, we also uncover that the dimensionality of the system significantly influences how flatbands can be controlled in a non-Hermitian manner. Our findings hold great potential for manipulating how light behaves and localizes in open systems that aren't Hermitian, opening doors to new ways of managing light dynamics and localization in various applications.
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Why is it important?
We are the first to achieve beneficial manipulation of multi-flatband systems using solely non-Hermitian methods. The flatbands remain completely flat before reaching exceptional points. Even beyond the exceptional point, one of the flatbands can still maintain a completely flat state.
Perspectives
As a researcher deeply involved in this study, I find our findings immensely exciting and groundbreaking. The ability to manipulate flatbands system in a non-Hermitian manner represents a significant leap in our understanding of light dynamics. Witnessing how these flatbands transform and maintain their unique properties even beyond exceptional points is nothing short of fascinating. Personally, I see this work as a stepping stone toward unlocking new possibilities in photonics and optical engineering. It's incredibly rewarding to contribute to a field that holds such promise for revolutionizing technologies and applications in the near future.
Shirong Lin
Great Bay University
Read the Original
This page is a summary of: Controllable flatbands via non-Hermiticity, Applied Physics Letters, November 2023, American Institute of Physics,
DOI: 10.1063/5.0174456.
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