Letter | Published:

Symmetry-breaking-induced nonlinear optics at a microcavity surface

Nature Photonicsvolume 13pages2124 (2019) | Download Citation


Second-order nonlinear optical processes lie at the heart of many applications in both classical and quantum regimes1,2,3. Inversion symmetry, however, rules out the second-order nonlinear electric-dipole response1,4,5 in materials widely adopted in integrated photonics (for example, SiO2, Si and Si3N4). Here, we report nonlinear optics induced by symmetry breaking6,7,8,9,10 at the surface of an ultrahigh-Q silica microcavity under a sub-milliwatt continuous-wave pump. By dynamically coordinating the double-resonance phase matching, a second harmonic is achieved with an unprecedented conversion efficiency of 0.049% W−1, 14 orders of magnitude higher than that of the non-enhancement case11. In addition, the nonlinear effect from the intrinsic symmetry breaking at the surface8,12 can be identified unambiguously, with guided control of the pump polarization and the recognition of the second-harmonic mode distribution. This work not only extends the emission frequency range of silica photonic devices, but also lays the groundwork for applications in ultra-sensitive surface analysis.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Boyd, R. W. Nonlinear Optics (Elsevier, New York, 2003).

  2. 2.

    Pereira, S., Xiao, M., Kimble, H. & Hall, J. Generation of squeezed light by intracavity frequency doubling. Phys. Rev. A 38, 4931–4934 (1988).

  3. 3.

    Kwiat, P. G. et al. New high-intensity source of polarization-entangled photon pairs. Phys. Rev. Lett. 75, 4337–4341 (1995).

  4. 4.

    Leuthold, J., Koos, C. & Freude, W. Nonlinear silicon photonics. Nat. Photon. 4, 535–544 (2010).

  5. 5.

    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).

  6. 6.

    Bloembergen, N., Chang, R. K., Jha, S. & Lee, C. Optical second-harmonic generation in reflection from media with inversion symmetry. Phys. Rev. 174, 813–822 (1968).

  7. 7.

    Shen, Y. R. Surface properties probed by second-harmonic and sum-frequency generation. Nature 337, 519–525 (1989).

  8. 8.

    Shen, Y. R. in Fundamentals of Sum-Frequency Spectroscopy Ch. 3 (Cambridge University Press, Cambridge, UK, 2016).

  9. 9.

    Cazzanelli, M. & Schilling, J. Second order optical nonlinearity in silicon by symmetry breaking. Appl. Phys. Rev. 3, 011104 (2016).

  10. 10.

    Billat, A. et al. Large second harmonic generation enhancement in Si3N4 waveguides by all-optically induced quasi-phase-matching. Nat. Commun. 8, 1016 (2017).

  11. 11.

    Tian, C. & Shen, Y. R. Recent progress on sum-frequency spectroscopy. Surf. Sci. Rep. 69, 105–131 (2014).

  12. 12.

    Sun, S., Tian, C. & Shen, Y. R. Surface sum-frequency vibrational spectroscopy of nonpolar media. Proc. Natl Acad. Sci. USA 112, 5883–5887 (2015).

  13. 13.

    Jacobsen, R. S. et al. Strained silicon as a new electro-optic material. Nature 441, 199–202 (2006).

  14. 14.

    Cazzanelli, M. et al. Second-harmonic generation in silicon waveguides strained by silicon nitride. Nat. Mater. 11, 148–154 (2012).

  15. 15.

    Timurdogan, E., Poulton, C. V., Byrd, M. & Watts, M. Electric field-induced second-order nonlinear optical effects in silicon waveguides. Nat. Photon. 11, 200–206 (2017).

  16. 16.

    Heinz, T. F., Tom, H. W. K. & Shen, Y. R. Determination of molecular orientation of monolayer adsorbates by optical second-harmonic generation. Phys. Rev. A 28, 1883–1885 (1983).

  17. 17.

    Corn, R. M. & Higgins, D. A. Optical second harmonic generation as a probe of surface chemistry. Chem. Rev. 94, 107–125 (1994).

  18. 18.

    Qian, S.-X., Snow, J. B., Tzeng, H.-M. & Chang, R. K. Lasing droplets: highlighting the liquid-air interface by laser emission. Science 231, 486–488 (1986).

  19. 19.

    Braginsky, V., Gorodetsky, M. & Ilchenko, V. Quality-factor and nonlinear properties of optical whispering gallery modes. Phys. Lett. A 137, 393–397 (1989).

  20. 20.

    Lin, H.-B. & Campillo, A. CW nonlinear optics in droplet microcavities displaying enhanced gain. Phys. Rev. Lett. 73, 2440–2443 (1994).

  21. 21.

    Carmon, T. & Vahala, K. J. Visible continuous emission from a silica microphotonic device by third-harmonic generation. Nat. Phys. 3, 430–435 (2007).

  22. 22.

    Fürst, J. et al. Naturally phase-matched second-harmonic generation in a whispering-gallery-mode resonator. Phys. Rev. Lett. 104, 153901 (2010).

  23. 23.

    Del’ Haye, P. et al. Optical frequency comb generation from a monolithic microresonator. Nature 450, 1214–1217 (2007).

  24. 24.

    Breunig, I. Three wave mixing in whispering gallery resonators. Laser Photon. Rev. 10, 569–587 (2016).

  25. 25.

    Jiang, X. et al. Chaos-assisted broadband momentum transformation in optical microresonators. Science 358, 344–347 (2017).

  26. 26.

    Gouveia, M. A. et al. Second harmonic generation and enhancement in microfibers and loop resonators. Appl. Phys. Lett. 102, 201120 (2013).

  27. 27.

    Lettieri, S. et al. Second-harmonic generation in hydrogenated amorphous-Si1−xNx doubly resonant microcavities with periodic dielectric mirrors. Appl. Phys. Lett. 87, 191110 (2005).

  28. 28.

    Levy, J. S., Foster, M. A., Gaeta, A. L. & Lipson, M. Harmonic generation in silicon nitride ring resonators. Opt. Express 19, 11415–11421 (2011).

  29. 29.

    Asano, M. et al. Visible light emission from a silica microbottle resonator by second- and third-harmonic generation. Opt. Lett. 41, 5793–5796 (2016).

  30. 30.

    Xue, X. et al. Second-harmonic-assisted four-wave mixing in chip-based microresonator frequency comb generation. Light Sci. Appl. 6, e16253 (2017).

  31. 31.

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

  32. 32.

    Ward, J. & Benson, O. WGM microresonators: sensing, lasing and fundamental optics with microspheres. Laser Photon. Rev. 5, 553–570 (2011).

  33. 33.

    Carmon, T., Yang, L. & Vahala, K. J. Dynamical thermal behavior and thermal self-stability of microcavities. Opt. Express 12, 4742–4750 (2004).

  34. 34.

    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).

  35. 35.

    Andrews, D. L. & Allcock, P. Optical Harmonics in Molecular Systems: Quantum Electrodynamical Theory (Wiley Online Library, Weinheim, 2002).

Download references


The authors thank K. J. Vahala, M. Lončar, C. Tian, Y. R. Shen, T. F. Heinz, X. Yi, D. Lippolis, H. Wang, Q.-F. Yang and L. Shao for helpful discussions. This project is supported by the National Natural Science Foundation of China (grant nos. 11825402, 11654003, 61435001, 11474011, 61611540346 and 11527901), the National Key R&D Program of China (grant no. 2016YFA0301302), and the High-performance Computing Platform of Peking University.

Author information

Author notes

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

  2. These authors contributed equally: Xueyue Zhang, Qi-Tao Cao.


  1. State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University, Beijing, People’s Republic of China

    • Xueyue Zhang
    • , Qi-Tao Cao
    • , Qihuang Gong
    •  & Yun-Feng Xiao
  2. Department of microelectronics and nanoelectronics, Tsinghua University, Beijing, People’s Republic of China

    • Xueyue Zhang
    •  & Yu-xi Liu
  3. Collaborative Innovation Center of Extreme Optics, Shanxi University, Shanxi, People’s Republic of China

    • Qi-Tao Cao
    • , Qihuang Gong
    •  & Yun-Feng Xiao
  4. Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore

    • Zhuo Wang
    •  & Cheng-Wei Qiu
  5. Institute of Microelectronics, Tsinghua University, Beijing, People’s Republic of China

    • Yu-xi Liu
  6. Department of Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA

    • Lan Yang


  1. Search for Xueyue Zhang in:

  2. Search for Qi-Tao Cao in:

  3. Search for Zhuo Wang in:

  4. Search for Yu-xi Liu in:

  5. Search for Cheng-Wei Qiu in:

  6. Search for Lan Yang in:

  7. Search for Qihuang Gong in:

  8. Search for Yun-Feng Xiao in:


X.Z. and Q.-T.C. fabricated the microcavity samples, built the experimental set-up and carried out measurements. X.Z., Q.-T.C., Z.W., Y.-x.L. and C.-W.Q. built the theoretical model and peformed numerical simulations. Y.-F.X., X.Z., Q.-T.C., C.-W.Q. and L.Y. wrote the manuscript with input from all co-authors. All the authors analysed the data and contributed to the discussion. Y.-F.X. conceived the idea and designed the experiment. Y.-F.X. and Q.G. supervised the project.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Yun-Feng Xiao.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–5, Supplementary Tables 1–2 and additional information about the work.

  2. Supplementary Video 1

    Dynamic phase-matching process.

About this article

Publication history




Issue Date



Further reading