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Floquet topological states in time-varying metasurfaces
Qian Ma1, Jian Wei You1, Long Chen1
1State Key Laboratory of Millimeter Waves and Institute of Electromagnetic Space, Southeast University, Nanjing, China.
Science Advances
|September 26, 2025
Summary
Researchers developed a programmable metasurface to study Floquet topological states. Increasing modulation frequency induces topological transitions and anomalous chiral edge states, enabling robust unidirectional propagation and harmonic generation.
Area of Science:
- Condensed matter physics
- Quantum physics
- Photonics
Background:
- Floquet systems provide a nonequilibrium periodic platform for exploring novel phases of matter.
- Existing research primarily focuses on linear, closed systems with spatially periodic driving.
Purpose of the Study:
- To introduce a programmable time-varying metasurface for investigating Floquet topological states.
- To explore topological transitions and anomalous edge states in open systems.
Main Methods:
- Utilizing a programmable time-varying metasurface.
- Investigating topological transitions in response to modulation frequency.
- Analyzing harmonic generation via Floquet edge states.
- Experimentally confirming Floquet harmonic bands and edge state propagation.
Main Results:
- A topological transition occurs with increasing modulation frequency.
- Anomalous chiral edge states emerge within Floquet harmonic bandgaps.
- The open metasurface facilitates harmonic generation.
- Robust unidirectional propagation of edge states is experimentally confirmed.
Conclusions:
- The developed metasurface serves as a unique platform for exploring Floquet topological physics.
- The system demonstrates potential for diverse applications in dynamic wave manipulation.
- Programmable coding schemes allow for reconfigurable propagation paths.
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