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Mirror symmetric on-chip frequency circulation of light


Integrated circulators and isolators are important for developing on-chip optical technologies such as laser cavities, communication systems and quantum information processors. These devices seem to inherently require mirror symmetry breaking to separate backwards from forwards propagation, and thus existing implementations rely on magnetic materials or interactions driven by propagating waves. By contrast to past works, we exhibit a mirror-symmetric non-reciprocal device that comprises three coupled photonic resonators implemented in thin-film lithium niobate. Applying radiofrequency modulation, we drive conversion between the frequency eigenmodes of this system. We measure nearly 40 dB of isolation for approximately 75 mW of radiofrequency power near 1,550 nm. We simultaneously generate non-reciprocal conversion between all of the eigenmodes to demonstrate circulation. Mirror-symmetric circulation simplifies the fabrication and operation of non-reciprocal integrated devices. Finally, we consider applications of such on-chip isolators and circulators, such as full-duplex isolation within a single waveguide.

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Fig. 1: Device structure and resonant system.
Fig. 2: Isolation versus microwave phase condition Δϕ = 2ϕ1 − ϕ2.
Fig. 3: Experiment characterization scheme.
Fig. 4: Isolation versus microwave power.

Data availability

The data comprising Fig. 4 and Supplementary Fig. 8 are available on Zenodo at Additional data generated and analysed in this study are available from the corresponding author on reasonable request.


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J.F.H. acknowledges support from the National Science Foundation Graduate Research Fellowship Program (grant no. DGE-1656518). V.A. acknowledges support by the Stanford Q-FARM Bloch Fellowship Program. We acknowledge the support of an AFOSR MURI project (grant no. FA9550-18-1-0379) and the National Science Foundation under award no. ECCS-1820938. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award no. ECCS-2026822. Work was performed in part at the nano@stanford laboratories, which are supported by the National Science Foundation as part of the National Nanotechnology Coordinated Infrastructure under award no. ECCS-1542152. We would like to thank W. Jiang and C. J. Sarabalis for insightful and helpful discussions.

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Authors and Affiliations



J.F.H. fabricated the device. J.F.H. and V.A. led the experimental effort. J.W. developed the device operating theory and characterized theoretical device performance. J.F.H, J.D.W. and J.W. determined physical device designs. J.D.W. assisted in early experimentation. A.H.S.-N and S.F. provided experimental and theoretical guidance and support for this experiment.

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Correspondence to Jason F. Herrmann or Amir H. Safavi-Naeini.

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Nature Photonics thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary information

Supplementary Analysis and Discussion, Sections 1–8, Figs. 1–8 and Tables 1–3.

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Herrmann, J.F., Ansari, V., Wang, J. et al. Mirror symmetric on-chip frequency circulation of light. Nat. Photon. 16, 603–608 (2022).

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