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Topological soliton frequency comb in nanophotonic lithium niobate

Nature volume 652, pages 76–81 (2026)Cite this article

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Abstract

Frequency combs have revolutionized metrology, ranging and optical clocks1, motivating substantial efforts on the development of chip-scale comb sources2,3. Some on-chip comb sources exist and have been implemented through electro-optic modulation4,5, mode-locked lasers6,7, quantum cascade lasers8,9,10 or soliton formation by Kerr nonlinearity11,12. However, widespread deployment of on-chip comb sources has remained elusive, as they still require radiofrequency sources, high-Q (high-quality factor) resonators or complex stabilization schemes while facing efficiency challenges. Here, we demonstrate an on-chip frequency comb source based on the integration of a lithium niobate nanophotonic circuit with a semiconductor laser that can alleviate these challenges. We show the formation of temporal topological solitons in an on-chip nanophotonic parametric oscillator with quadratic nonlinearity and low finesse. These solitons, independent of the dispersion regime, consist of phase defects separating two π-out-of-phase continuous wave solutions at the signal frequency, which is half the input pump frequency13,14. We use on-chip cross-correlation for temporal measurements and confirm formation of topological solitons as short as 60 fs around 2 μm, in agreement with a generalized parametrically forced Ginzburg–Landau theory15,16,17. Moreover, we demonstrate a proof-of-concept turn-key operation of a hybrid-integrated source of topological frequency comb. Topological solitons are potential candidates for the development of integrated comb sources, which are dispersion-sign agnostic and do not require high-Q resonators or high-speed modulators, and can provide access to hard-to-reach spectral regions, including mid-infrared regions18.

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Fig. 1: Topological soliton concept.
Fig. 2: Theoretical analysis of temporal topological solitons.
Fig. 3: Temporal and spectral characteristics of topological solitons.
Fig. 4: Integrated topological soliton frequency comb source.

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Data availability

The data that support the findings of this study are available from the corresponding authors upon request.

References

  1. Fortier, T. & Baumann, E. 20 years of developments in optical frequency comb technology and applications. Commun. Phys. 2, 153 (2019).

    Article  Google Scholar 

  2. Pasquazi, A. et al. Micro-combs: a novel generation of optical sources. Phys. Rep. 729, 1–81 (2018).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  3. Gaeta, A. L., Lipson, M. & Kippenberg, T. J. Photonic-chip-based frequency combs. Nat. Photon. 13, 158–169 (2019).

    Article  ADS  CAS  Google Scholar 

  4. Zhang, M. et al. Broadband electro-optic frequency comb generation in a lithium niobate microring resonator. Nature 568, 373–377 (2019).

    Article  ADS  CAS  PubMed  Google Scholar 

  5. Stokowski, H. S. et al. Integrated frequency-modulated optical parametric oscillator. Nature 627, 95–100 (2024).

    Article  ADS  CAS  PubMed  Google Scholar 

  6. Davenport, M. L., Liu, S. & Bowers, J. E. Integrated heterogeneous silicon/III-V mode-locked lasers. Photonics Res. 6, 468–478 (2018).

    Article  CAS  Google Scholar 

  7. Guo, Q. et al. Ultrafast mode-locked laser in nanophotonic lithium niobate. Science 382, 708–713 (2023).

    Article  ADS  CAS  PubMed  Google Scholar 

  8. Hugi, A., Villares, G., Blaser, S., Liu, H. C. & Faist, J. Mid-infrared frequency comb based on a quantum cascade laser. Nature 492, 229–233 (2012).

    Article  ADS  CAS  PubMed  Google Scholar 

  9. Meng, B. et al. Dissipative Kerr solitons in semiconductor ring lasers. Nat. Photon. 16, 142–147 (2022).

    Article  ADS  CAS  Google Scholar 

  10. Kazakov, D. et al. Driven bright solitons on a mid-infrared laser chip. Nature 641, 83–89 (2025).

    Article  ADS  CAS  PubMed  Google Scholar 

  11. Leo, F. et al. Temporal cavity solitons in one-dimensional Kerr media as bits in an all-optical buffer. Nat. Photon. 4, 471–476 (2010).

    Article  ADS  CAS  Google Scholar 

  12. Herr, T. et al. Temporal solitons in optical microresonators. Nat. Photon. 8, 145–152 (2014).

    Article  ADS  CAS  Google Scholar 

  13. Trillo, S., Haelterman, M. & Sheppard, A. Stable topological spatial solitons in optical parametric oscillators. Opt. Lett. 22, 970–972 (1997).

    Article  ADS  CAS  PubMed  Google Scholar 

  14. Parra-Rivas, P., Gelens, L., Hansson, T., Wabnitz, S. & Leo, F. Frequency comb generation through the locking of domain walls in doubly resonant dispersive optical parametric oscillators. Opt. Lett. 44, 2004–2007 (2019).

    Article  ADS  PubMed  Google Scholar 

  15. Leo, F. et al. Walk-off-induced modulation instability, temporal pattern formation, and frequency comb generation in cavity-enhanced second-harmonic generation. Phys. Rev. Lett. 116, 033901 (2016).

    Article  ADS  CAS  PubMed  Google Scholar 

  16. Mosca, S. et al. Modulation instability induced frequency comb generation in a continuously pumped optical parametric oscillator. Phys. Rev. Lett. 121, 093903 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  17. Parra-Rivas, P., Mas Arabí, C. & Leo, F. Dissipative localized states and breathers in phase-mismatched singly resonant optical parametric oscillators: bifurcation structure and stability. Phys. Rev. Res. 4, 013044 (2022).

    Article  CAS  Google Scholar 

  18. Schliesser, A., Picqué, N. & Hänsch, T. W. Mid-infrared frequency combs. Nat. Photon. 6, 440–449 (2012).

    Article  ADS  CAS  Google Scholar 

  19. Zhang, J. et al. Ultrabroadband integrated electro-optic frequency comb in lithium tantalate. Nature 637, 1096–1103 (2025).

    Article  ADS  CAS  PubMed  Google Scholar 

  20. Buryak, A. V., Trapani, P. D., Skryabin, D. V. & Trillo, S. Optical solitons due to quadratic nonlinearities: from basic physics to futuristic applications. Phys. Rep. 370, 63–235 (2002).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  21. Nie, M., Xie, Y., Li, B. & Huang, S.-W. Photonic frequency microcombs based on dissipative Kerr and quadratic cavity solitons. Prog. Quantum Electron. 86, 100437 (2022).

    Article  Google Scholar 

  22. Jankowski, M. et al. Temporal simultons in optical parametric oscillators. Phys. Rev. Lett. 120, 053904 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  23. Nie, M., Musgrave, J. & Huang, S.-W. Dissipative quadratic soliton in the cascaded nonlinearity limit. Nat. Commun. 17, 502 (2025).

    Article  PubMed  PubMed Central  Google Scholar 

  24. O’Donnell, C. F., Kumar, S. C., Paoletta, T. & Ebrahim-Zadeh, M. Widely tunable femtosecond soliton generation in a fiber-feedback optical parametric oscillator. Optica 7, 426–433 (2020).

    Article  ADS  Google Scholar 

  25. Roy, A. et al. Temporal walk-off induced dissipative quadratic solitons. Nat. Photon. 16, 162–168 (2022).

    Article  ADS  CAS  Google Scholar 

  26. Lu, J. et al. Two-colour dissipative solitons and breathers in microresonator second-harmonic generation. Nat. Commun. 14, 2798 (2023).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  27. Bruch, A. W. et al. Pockels soliton microcomb. Nat. Photon. 15, 21–27 (2020).

    Article  ADS  MathSciNet  Google Scholar 

  28. Mermin, N. D. The topological theory of defects in ordered media. Rev. Mod. Phys. 51, 591–648 (1979).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  29. Manton, N. & Sutcliffe, P. Topological Solitons. Cambridge Monographs on Mathematical Physics (Cambridge Univ. Press, 2004).

  30. Roy, A., Parto, M., Nehra, R., Leefmans, C. & Marandi, A. Topological optical parametric oscillation. Nanophotonics 11, 1611–1618 (2022).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  31. Flower, C. J. et al. Observation of topological frequency combs. Science 384, 1356–1361 (2024).

    Article  ADS  CAS  PubMed  Google Scholar 

  32. Tikan, A. et al. Emergent nonlinear phenomena in a driven dissipative photonic dimer. Nat. Phys. 17, 604–610 (2021).

    Article  CAS  Google Scholar 

  33. Gustave, F. et al. Dissipative phase solitons in semiconductor lasers. Phys. Rev. Lett. 115, 043902 (2015).

    Article  ADS  CAS  PubMed  Google Scholar 

  34. Prati, F. et al. Soliton dynamics of ring quantum cascade lasers with injected signal. Nanophotonics 10, 195–207 (2021).

    Article  Google Scholar 

  35. Garbin, B. et al. Dissipative polarization domain walls in a passive coherently driven Kerr resonator. Phys. Rev. Lett. 126, 023904 (2021).

    Article  ADS  CAS  PubMed  Google Scholar 

  36. Coen, S. et al. Nonlinear topological symmetry protection in a dissipative system. Nat. Commun. 15, 1398 (2024).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  37. Oppo, G.-L., Scroggie, A. J. & Firth, W. J. From domain walls to localized structures in degenerate optical parametric oscillators. J. Opt. B Quantum Semiclassical Opt. 1, 133–138 (1999).

    Article  ADS  Google Scholar 

  38. Taranenko, V. B., Staliunas, K. & Weiss, C. O. Pattern formation and localized structures in degenerate optical parametric mixing. Phys. Rev. Lett. 81, 2236–2239 (1998).

    Article  ADS  CAS  Google Scholar 

  39. Esteban-Martín, A., Taranenko, V. B., Roldán, E. & Valcárcel, G. J. D. Control and steering of phase domain walls. Opt. Express 13, 3631–3636 (2005).

    Article  ADS  PubMed  Google Scholar 

  40. Zacharias, T. et al. Energy-efficient ultrashort-pulse characterization using nanophotonic parametric amplification. ACS Photonics 12, 1316–1320 (2025).

    Article  CAS  Google Scholar 

  41. Marandi, A., Leindecker, N. C., Vodopyanov, K. L. & Byer, R. L. All-optical quantum random bit generation from intrinsically binary phase of parametric oscillators. Opt. Express 20, 19322–19330 (2012).

    Article  ADS  PubMed  Google Scholar 

  42. Ledezma, L. et al. Octave-spanning tunable infrared parametric oscillators in nanophotonics. Sci. Adv. 9, eadf9711 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  43. Roy, A. et al. Visible-to-mid-IR tunable frequency comb in nanophotonics. Nat. Commun. 14, 6549 (2023).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  44. Kellner, J., Sabatti, A., Maeder, A. & Grange, R. Low threshold integrated optical parametric oscillator with a compact Bragg resonator. Optica 12, 702–707 (2025).

    Article  ADS  CAS  Google Scholar 

  45. Marandi, A., Wang, Z., Takata, K., Byer, R. L. & Yamamoto, Y. Network of time-multiplexed optical parametric oscillators as a coherent Ising machine. Nat. Photon. 8, 937–942 (2014).

    Article  ADS  CAS  Google Scholar 

  46. Englebert, N. et al. Parametrically driven Kerr cavity solitons. Nat. Photon. 15, 857–861 (2021).

    Article  ADS  Google Scholar 

  47. Ferdous, F. et al. Spectral line-by-line pulse shaping of on-chip microresonator frequency combs. Nat. Photon. 5, 770–776 (2011).

    Article  ADS  CAS  Google Scholar 

  48. Xue, X. et al. Mode-locked dark pulse Kerr combs in normal-dispersion microresonators. Nat. Photon. 9, 594–600 (2015).

    Article  ADS  CAS  Google Scholar 

  49. Ledezma, L. et al. Intense optical parametric amplification in dispersion-engineered nanophotonic lithium niobate waveguides. Optica 9, 303–308 (2022).

    Article  ADS  Google Scholar 

  50. Wang, C. et al. Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages. Nature 562, 101–104 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  51. Riemensberger, J. et al. Massively parallel coherent laser ranging using a soliton microcomb. Nature 581, 164–170 (2020).

    Article  ADS  CAS  PubMed  Google Scholar 

  52. Marin-Palomo, P. et al. Microresonator-based solitons for massively parallel coherent optical communications. Nature 546, 274–279 (2017).

    Article  ADS  CAS  PubMed  Google Scholar 

  53. Roy, A., Nehra, R., Langrock, C., Fejer, M. & Marandi, A. Non-equilibrium spectral phase transitions in coupled nonlinear optical resonators. Nat. Phys. 19, 427–434 (2023).

    Article  CAS  Google Scholar 

  54. Jankowski, M. et al. Ultrabroadband nonlinear optics in nanophotonic periodically poled lithium niobate waveguides. Optica 7, 40–46 (2020).

    Article  ADS  CAS  Google Scholar 

  55. Trebino, R. Frequency-Resolved Optical Gating: The Measurement of Ultrashort Laser Pulses (Springer, 2000).

  56. Cole, D. C., Lamb, E. S., Del’Haye, P., Diddams, S. A. & Papp, S. B. Soliton crystals in Kerr resonators. Nat. Photon. 11, 671–676 (2017).

    Article  ADS  CAS  Google Scholar 

  57. Karpov, M. et al. Dynamics of soliton crystals in optical microresonators. Nat. Phys. 15, 1071–1077 (2019).

    Article  CAS  Google Scholar 

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Acknowledgements

We thank F. Leo for the discussions. The device nanofabrication was performed at the Kavli Nanoscience Institute (KNI) at Caltech. We acknowledge support from DARPA award D23AP00158, ARO grant no. W911NF-23-1-0048, NSF grant nos. 2408297 and 1918549, AFOSR award FA9550-23-1-0755, the Center for Sensing to Intelligence at Caltech, the Alfred P. Sloan Foundation, and NASA/JPL. N.E. acknowledges support from the Belgian American Educational Foundation (B.A.E.F.), the SofinaBoël Fund and the Horizon Europe research and innovation programme of the European Union under the Marie Skłodowska–Curie grant agreement no. 101103780. P.P.-R. is supported by the MCIU/AEI/10.13039/501100011033 and the FSE+ under the grant no. RYC2023-043590-I.

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Author notes

  1. These authors contributed equally: Nicolas Englebert, Robert M. Gray

Authors and Affiliations

  1. Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA

    Nicolas Englebert, Robert M. Gray, Luis Ledezma, Ryoto Sekine, Thomas Zacharias, Rithvik Ramesh & Alireza Marandi

  2. PINC Technologies, Pasadena, CA, USA

    Ryoto Sekine

  3. Department of Applied Physics, California Institute of Technology, Pasadena, CA, USA

    Benjamin K. Gutierrez & Alireza Marandi

  4. Nonlinear and Materials Physics Group, Department of Chemistry and Physics, University of Almeria, Almeria, Spain

    Pedro Parra-Rivas

  5. Materials for Solar Thermal and Photovoltaic Energy Unit, CIESOL Research Center on Solar Energy, Joint Center UAL-CIEMAT, University of Almeria, Almeria, Spain

    Pedro Parra-Rivas

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Contributions

N.E. and A.M. conceived the project. N.E. and R.M.G. performed the experiments. T.Z. and R.R. assisted with the temporal measurements using the DOPA chip. N.E. simulated the mean-field model and analysed the results. L.L. and R.S. designed, fabricated and characterized the DOPO and the DOPA chips used in the experiments. B.K.G. assisted with DOPO chip design. P.P.-R. performed the theoretical analyses. N.E. and A.M. wrote the paper with inputs from all authors. All authors discussed the results and contributed to the final manuscript. A.M. supervised the project.

Corresponding authors

Correspondence to Nicolas Englebert, Pedro Parra-Rivas or Alireza Marandi.

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Competing interests

R.M.G., B.K.G, L.L. and A.M. are inventors on a US patent application US18/543,950. L.L. and A.M. are inventors on a US patent 11,226,538. R.S., L.L. and A.M. are involved in developing photonic integrated nonlinear circuits at PINC Technologies. R.S., L.L. and A.M. have an equity interest in PINC Technologies. The remaining authors declare no competing interests.

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Nature thanks Dmitry Kazakov, Lukas Maczewsky, Johann Riemensberger, Baile Zhang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Englebert, N., Gray, R.M., Ledezma, L. et al. Topological soliton frequency comb in nanophotonic lithium niobate. Nature 652, 76–81 (2026). https://doi.org/10.1038/s41586-026-10292-2

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