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Towards Floquet Chern insulators of light
Jicheng Jin1, Li He1,2, Jian Lu1,3
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA.
Nature Nanotechnology
|September 5, 2025
Summary
Researchers demonstrated topological phases in driven nonlinear photonic crystals. Circularly polarized light created a topological gap, showing potential for nonlinear optoelectronics.
Area of Science:
- Topological photonics
- Nonlinear optics
- Condensed matter physics
Background:
- Topological photonics utilizes topological phases for robust optical systems.
- These phases are typically observed in linear optical systems.
- Floquet engineering offers new pathways to realize topological phases.
Purpose of the Study:
- To experimentally investigate Floquet Chern insulators in periodically driven nonlinear photonic crystals.
- To control topological phases using polarization and frequency of the driving field.
- To explore the role of optical nonlinearity in topological phenomena.
Main Methods:
- Experimental realization of periodically driven nonlinear photonic crystals.
- Transient sum-frequency generation spectroscopy for band structure analysis.
- Theoretical analysis using Chern number to characterize topological phases.
Main Results:
- Observed strong hybridization of Floquet photonic bands.
- Demonstrated a gapless spectrum under linear polarization and a gapped spectrum under circular polarization.
- Confirmed the topological nature of the Floquet gap induced by time-reversal symmetry breaking.
Conclusions:
- Circularly polarized driving fields can induce topological phases in nonlinear photonic systems.
- This work highlights the interplay between nonlinearity and topology in photonics.
- Opens avenues for novel nonlinear optoelectronic devices based on topological principles.
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