Optical microresonators are essential to a broad range of technologies and scientific disciplines. However, many of their applications rely on discrete devices to attain challenging combinations of ultra-low-loss performance (ultrahigh Q) and resonator design requirements. This prevents access to scalable fabrication methods for photonic integration and lithographic feature control. Indeed, finding a microfabrication bridge that connects ultrahigh-Q device functions with photonic circuits is a priority of the microcavity field. Here, an integrated resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance to integrated systems that has been the exclusive domain of discrete silica and crystalline microcavity devices. Two distinctly different devices are demonstrated: soliton sources with electronic repetition rates and high-coherence/low-threshold Brillouin lasers. This multi-device capability and performance from a single integrated cavity platform represents a critical advance for future photonic circuits and systems.

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  1. 1.

    Vahala, K. J. Optical microcavities. Nature 424, 839–846 (2003).

  2. 2.

    Kippenberg, T. J., Holzwarth, R. & Diddams, S. A. Microresonator-based optical frequency combs. Science 332, 555–559 (2011).

  3. 3.

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

  4. 4.

    Yi, X., Yang, Q.-F., Yang, K. Y., Suh, M.-G. & Vahala, K. Soliton frequency comb at microwave rates in a high-Q silica microresonator. Optica 2, 1078–1085 (2015).

  5. 5.

    Brasch, V. et al. Photonic chip-based optical frequency comb using soliton Cherenkov radiation. Science 351, 357–360 (2016).

  6. 6.

    Joshi, C. et al. Thermally controlled comb generation and soliton modelocking in microresonators. Opt. Lett. 41, 2565–2568 (2016).

  7. 7.

    Wang, P.-H. et al. Intracavity characterization of micro-comb generation in the single-soliton regime. Opt. Express 24, 10890–10897 (2016).

  8. 8.

    Tomes, M. & Carmon, T. Photonic micro-electromechanical systems vibrating at X-band (11-GHz) rates. Phys. Rev. Lett. 102, 113601 (2009).

  9. 9.

    Grudinin, I. S., Matsko, A. B. & Maleki, L. Brillouin lasing with a CaF2 whispering gallery mode resonator. Phys. Rev. Lett. 102, 043902 (2009).

  10. 10.

    Lee, H. et al. Chemically etched ultrahigh-Q wedge-resonator on a silicon chip. Nat. Photon. 6, 369–373 (2012).

  11. 11.

    Morrison, B. et al. Compact Brillouin devices through hybrid integration on silicon. Optica 4, 847–854 (2017).

  12. 12.

    Otterstrom, N. T., Behunin, R. O., Kittlaus, E. A., Wang, Z. & Rakich, P. T. A silicon Brillouin laser. Preprint at http://arXiv.org/abs/1705.05813 (2017).

  13. 13.

    Vollmer, F. & Arnold, S. Whispering-gallery-mode biosensing: label-free detection down to single molecules. Nat. Methods 5, 591–596 (2008).

  14. 14.

    Vollmer, F. & Yang, L. Label-free detection with high-Q microcavities: a review of biosensing mechanisms for integrated devices. Nanophotonics 1, 267–291 (2012).

  15. 15.

    Kippenberg, T. J. & Vahala, K. J. Cavity optomechanics: back-action at the mesoscale. Science 321, 1172–1176 (2008).

  16. 16.

    Kippenberg, T. J., Spillane, S. M. & Vahala, K. J. Kerr-nonlinearity optical parametric oscillation in an ultrahigh-Q toroid microcavity. Phys. Rev. Lett. 93, 083904 (2004).

  17. 17.

    Savchenkov, A. A. et al. Low threshold optical oscillations in a whispering gallery mode CaF2 resonator. Phys. Rev. Lett. 93, 243905 (2004).

  18. 18.

    Spillane, S., Kippenberg, T. & Vahala, K. Ultralow-threshold Raman laser using a spherical dielectric microcavity. Nature 415, 621–623 (2002).

  19. 19.

    Matsko, A. B., Savchenkov, A. A., Yu, N. & Maleki, L. Whispering-gallery-mode resonators as frequency references. I. Fundamental limitations. J. Opt. Soc. Am. B 24, 1324–1335 (2007).

  20. 20.

    Alnis, J. et al. Thermal-noise-limited crystalline whispering-gallery-mode resonator for laser stabilization. Phys. Rev. A 84, 011804 (2011).

  21. 21.

    Lee, H. et al. Spiral resonators for on-chip laser frequency stabilization. Nat. Commun. 4, 2468 (2013).

  22. 22.

    Loh, W. et al. Dual-microcavity narrow-linewidth Brillouin laser. Optica 2, 225–232 (2015).

  23. 23.

    Aoki, T. et al. Observation of strong coupling between one atom and a monolithic microresonator. Nature 443, 671–674 (2006).

  24. 24.

    Xiong, C., Pernice, W. H. & Tang, H. X. Low-loss, silicon integrated, aluminum nitride photonic circuits and their use for electro-optic signal processing. Nano Lett. 12, 3562–3568 (2012).

  25. 25.

    Moss, D. J., Morandotti, R., Gaeta, A. L. & Lipson, M. New CMOS-compatible platforms based on silicon nitride and hydex for nonlinear optics. Nat. Photon. 7, 597–607 (2013).

  26. 26.

    Hausmann, B., Bulu, I., Venkataraman, V., Deotare, P. & Lončar, M. Diamond nonlinear photonics. Nat. Photon. 8, 369–374 (2014).

  27. 27.

    Lu, X., Lee, J. Y. & Lin, Q. High-frequency and high-quality silicon carbide optomechanical microresonators. Sci. Rep. 5, 17005 (2015).

  28. 28.

    Lu, X. et al. Heralding single photons from a high-Q silicon microdisk. Optica 3, 1331–1338 (2016).

  29. 29.

    Levy, J. S. et al. CMOS-compatible multiple-wavelength oscillator for on-chip optical interconnects. Nat. Photon. 4, 37–40 (2010).

  30. 30.

    Ramiro-Manzano, F., Prtljaga, N., Pavesi, L., Pucker, G. & Ghulinyan, M. A fully integrated high-Q whispering-gallery wedge resonator. Opt. Express 20, 22934–22942 (2012).

  31. 31.

    Jung, H., Xiong, C., Fong, K. Y., Zhang, X. & Tang, H. X. Optical frequency comb generation from aluminum nitride microring resonator. Opt. Lett. 38, 2810–2813 (2013).

  32. 32.

    Spencer, D. T., Bauters, J. F., Heck, M. J. & Bowers, J. E. Integrated waveguide coupled Si3N4 resonators in the ultrahigh-Q regime. Optica 1, 153–157 (2014).

  33. 33.

    Xuan, Y. et al. High-Q silicon nitride microresonators exhibiting low-power frequency comb initiation. Optica 3, 1171–1180 (2016).

  34. 34.

    Pfeiffer, M. H. et al. Photonic Damascene process for integrated high-Q microresonator based nonlinear photonics. Optica 3, 20–25 (2016).

  35. 35.

    Ji, X. et al. Ultra-low-loss on-chip resonators with sub-milliwatt parametric oscillation threshold. Optica 4, 619–624 (2017).

  36. 36.

    Grudinin, I. S., Ilchenko, V. S. & Maleki, L. Ultrahigh optical Q factors of crystalline resonators in the linear regime. Phys. Rev. A 74, 063806 (2006).

  37. 37.

    Armani, D., Kippenberg, T., Spillane, S. & Vahala, K. Ultra-high-Q toroid microcavity on a chip. Nature 421, 925–928 (2003).

  38. 38.

    Papp, S. B. & Diddams, S. A. Spectral and temporal characterization of a fused-quartz-microresonator optical frequency comb. Phys. Rev. A 84, 053833 (2011).

  39. 39.

    Papp, S. B. et al. Microresonator frequency comb optical clock. Optica 1, 10–14 (2014).

  40. 40.

    Spencer, D. T. et al. An integrated-photonics optical-frequency synthesizer. Preprint at http://arXiv.org/abs/1708.05228 (2017).

  41. 41.

    Li, J., Suh, M.-G. & Vahala, K. Microresonator Brillouin gyroscope. Optica 4, 346–348 (2017).

  42. 42.

    Liang, W. et al. Resonant microphotonic gyroscope. Optica 4, 114–117 (2017).

  43. 43.

    Maleki, L. Sources: the optoelectronic oscillator. Nat. Photon. 5, 728–730 (2011).

  44. 44.

    Li, J., Lee, H. & Vahala, K. J. Microwave synthesizer using an on-chip Brillouin oscillator. Nat. Commun. 4, 2097 (2013).

  45. 45.

    Li, J., Yi, X., Lee, H., Diddams, S. A. & Vahala, K. J. Electro-optical frequency division and stable microwave synthesis. Science 345, 309–313 (2014).

  46. 46.

    Liang, W. et al. High spectral purity Kerr frequency comb radio frequency photonic oscillator. Nat. Commun. 6, 7957 (2015).

  47. 47.

    Komljenovic, T. et al. Heterogeneous silicon photonic integrated circuits. J. Light. Technol. 34, 20–35 (2016).

  48. 48.

    Piels, M., Bauters, J. F., Davenport, M. L., Heck, M. J. & Bowers, J. E. Low-loss silicon nitride AWG demultiplexer heterogeneously integrated with hybrid III–V/silicon photodetectors. J. Light. Technol. 32, 817–823 (2014).

  49. 49.

    Spillane, S., Kippenberg, T., Painter, O. & Vahala, K. Ideality in a fiber-taper-coupled microresonator system for application to cavity quantum electrodynamics. Phys. Rev. Lett. 91, 043902 (2003).

  50. 50.

    Pfeiffer, M. H., Liu, J., Geiselmann, M. & Kippenberg, T. J. Coupling ideality of integrated planar high-Q microresonators. Phys. Rev. Appl. 7, 024026 (2017).

  51. 51.

    Pfeiffer, M. H. et al. Octave-spanning dissipative Kerr soliton frequency combs in Si3N4 microresonators. Optica 4, 684–691 (2017).

  52. 52.

    Jones, D. J. et al. Carrier-envelope phase control of femtosecond mode-locked lasers and direct optical frequency synthesis. Science 288, 635–639 (2000).

  53. 53.

    Li, Q. et al. Stably accessing octave-spanning microresonator frequency combs in the soliton regime. Optica 4, 193–203 (2017).

  54. 54.

    Yi, X., Yang, Q.-F., Yang, K. Y. & Vahala, K. Active capture and stabilization of temporal solitons in microresonators. Opt. Lett. 41, 2037–2040 (2016).

  55. 55.

    Suh, M.-G., Yang, Q.-F., Yang, K. Y., Yi, X. & Vahala, K. J. Microresonator soliton dual-comb spectroscopy. Science 354, 600–603 (2016).

  56. 56.

    Eggleton, B. J., Poulton, C. G. & Pant, R. Inducing and harnessing stimulated Brillouin scattering in photonic integrated circuits. Adv. Opt. Photon. 5, 536–587 (2013).

  57. 57.

    Li, J., Lee, H., Chen, T. & Vahala, K. J. Characterization of a high coherence, Brillouin microcavity laser on silicon. Opt. Express 20, 20170–20180 (2012).

  58. 58.

    Gorodetsky, M. L. & Grudinin, I. S. Fundamental thermal fluctuations in microspheres. J. Opt. Soc. Am. B 21, 697–705 (2004).

  59. 59.

    Matsko, A. B. & Maleki, L. On timing jitter of mode locked Kerr frequency combs. Opt. Express 21, 28862–28876 (2013).

  60. 60.

    Barkai, A. et al. Integrated silicon photonics for optical networks. J. Opt. Netw. 6, 25–47 (2007).

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We thank O. Painter and B. Baker for assistance with the PECVD silicon nitride process, H. Atwater and W.-H. Cheng for assistance with silica atomic layer deposition, M. Hunt for assistance with electron-beam microscopy, Y.-H. Lai for technical assistance, and A. Matsko and J. Bowers for helpful discussions. We also gratefully acknowledge the Defense Advanced Research Projects Agency under the DODOS (award no. HR0011-15-C-0055, sub award KK1540) and PRIGM:AIMS (grant no. N66001-16-1-4046) programs and the Kavli Nanoscience Institute.

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  1. These authors contributed equally: Ki Youl Yang, Dong Yoon Oh and Seung Hoon Lee.


  1. T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA, USA

    • Ki Youl Yang
    • , Dong Yoon Oh
    • , Seung Hoon Lee
    • , Qi-Fan Yang
    • , Xu Yi
    • , Boqiang Shen
    • , Heming Wang
    •  & Kerry Vahala


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K.Y.Y., D.Y.O., S.H.L. and K.V. conceived the fabrication process and resonator design. K.Y.Y., D.Y.O. and S.H.L. fabricated and tested the resonator structures with assistance from B.S. and H.W. K.Y.Y., D.Y.O., S.H.L., Q.F.Y., X.Y., B.S. and H.W. conducted soliton and Brillouin laser measurements. All authors analysed the data and contributed to writing the manuscript.

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The authors declare no competing interests.

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Correspondence to Kerry Vahala.

Supplementary information

  1. Supplementary Information

    This file describes the intrinsic cavity Q measured from 1,520–1,560 nm, investigation of cavity loss mechanism, waveguide–resonator coupling, the high-temperature annealing effect on cavity Q, and mode filtering.

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