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Giant Nonreciprocity and Gyration through Modulation-Induced Hatano-Nelson Coupling in Integrated Photonics.
Oğulcan E Örsel1, Jiho Noh2,3, Penghao Zhu4,5
1University of Illinois at Urbana-Champaign, Department of Electrical and Computer Engineering, Urbana, Illinois 61801 USA.
Physical Review Letters
|May 2, 2025
Summary
Researchers demonstrate dynamic control of asymmetric energy exchange in photonic systems, achieving exceptional points (EPs) and enabling novel nonreciprocal optical effects like giant contrast and photonic gyration.
Area of Science:
- Photonics
- Non-Hermitian Physics
- Integrated Optics
Background:
- Asymmetric energy exchange, or Hatano-Nelson couplings, are crucial for studying non-Hermitian physics.
- Implementing these nonreciprocal interactions in integrated photonics has been challenging.
Purpose of the Study:
- To demonstrate the feasibility of achieving asymmetric couplings in integrated photonic systems.
- To experimentally realize and control Hatano-Nelson type couplings using dynamic modulation.
- To explore novel nonreciprocal phenomena enabled by these engineered couplings.
Main Methods:
- Utilizing a two-resonator photonic molecule on a lithium niobate on insulator platform.
- Employing time-domain dynamic modulation via electro-optical modulation with RF stimuli.
- Experimentally tuning the Hatano-Nelson coupling strength and directionality.
Main Results:
- Achieved dynamic tuning of Hatano-Nelson couplings, surpassing previous asymmetry levels.
- Experimentally reached an exceptional point (EP) for the first time in this system.
- Demonstrated the ability to flip coupling signs by traversing the EP.
- Configured through-chain transport for giant optical contrast (~60 dB) and nonreciprocal phase contrast (photonic gyration).
Conclusions:
- Time-domain dynamic modulation provides a viable route for implementing asymmetric couplings in integrated photonics.
- The demonstrated control over Hatano-Nelson couplings opens new avenues for exploring non-Hermitian phenomena.
- This work paves the way for novel photonic devices with engineered nonreciprocity and advanced functionalities.
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