Multiple Exceptional Rings in One-Dimensional Perovskite Photonic Crystals

Area of Science:

• Condensed Matter Physics
• Topological Materials
• Non-Hermitian Systems

Background:

• Exceptional rings (ERs) are complex topological structures in non-Hermitian systems.
• Realizing ERs typically requires intricate designs and precise control, limiting experimental observations.

Purpose of the Study:

• To demonstrate that simple 1D non-Hermitian periodic systems can host multiple ERs.
• To explore the tunability of ERs through non-Hermitian loss.
• To establish a simplified platform for studying complex non-Hermitian topologies.

Main Methods:

• Theoretical investigation of 1D non-Hermitian periodic systems.
• Utilizing bulk Fermi torus in momentum space for tunability.
• Experimental realization using 1D perovskite photonic crystals.

Main Results:

• Successfully demonstrated the existence of one to four ERs and hybrid ERs in a simple 1D system.
• Tuning non-Hermitian loss was shown to control the number and type of ERs.
• Observed ERs and the associated bulk Fermi torus in photonic crystal experiments at visible frequencies.

Conclusions:

• Simple 1D non-Hermitian systems offer a versatile platform for realizing complex topological phenomena.
• The findings pave the way for optical-frequency applications leveraging non-Hermitian physics.
• This work significantly advances the experimental accessibility of high-dimensional non-Hermitian topologies.