Loss-Induced Bulk-Boundary Detachment in a Photonic Chern Insulator

Area of Science:

• Topological Photonics
• Non-Hermitian Physics
• Condensed Matter Physics

Background:

• Chiral edge states (CESs) in Chern insulators offer lossless, one-way propagation.
• Conventional CESs are limited to narrow bandwidths within band gaps.
• Intrinsic material loss is typically detrimental to topological transport.

Purpose of the Study:

• To investigate the role of engineered loss in broadening CES bandwidth.
• To explore non-Hermitian physics for enhanced topological photonic devices.
• To achieve broadband CES transport in a two-dimensional photonic Chern insulator.

Main Methods:

• Fabrication of a two-dimensional photonic Chern insulator with absorptive backgrounds.
• Leveraging non-Hermitian physics to introduce controlled bulk loss.
• Microwave experimental measurements to characterize CES propagation and bandwidth.

Main Results:

• Demonstrated multiple topological band gaps embedded in absorptive backgrounds.
• Observed loss-induced exceptional points leading to bulk-boundary detachment.
• Achieved a 27% relative bandwidth for CES across three band gaps.

Conclusions:

• Engineered loss can broaden chiral edge states (CESs) by inducing bulk-boundary detachment.
• This loss-induced detachment effect enables broadband topological transport.
• Highlights potential for designing novel photonic devices with moderate losses for enhanced functionality.