Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Electrically driven optical isolation through phonon-mediated photonic Autler–Townes splitting


Optical isolators today are exclusively built on magneto-optic principles but are not readily implemented within photonic integrated circuits. So far, no magnetless alternative1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22 has managed to simultaneously combine linearity (that is, no frequency shift), linear response (that is, input–output scaling), ultralow insertion loss and large directional contrast on-chip. Here we demonstrate an electrically driven optical isolator design that leverages the unbeatable transparency of a short, high-quality dielectric waveguide, with the strong attenuation from a critically coupled absorber. Our concept is implemented using a lithium niobate racetrack resonator in which phonon-mediated13 photonic Autler–Townes splitting10,16,23,24 breaks the chiral symmetry of the resonant modes. We demonstrate isolators at wavelengths one octave apart near 1,550 nm and 780 nm, fabricated from the same lithium-niobate-on-insulator wafer. Linear isolation is demonstrated with simultaneously <1 dB insertion loss, >39 dB contrast and 10 dB bandwidth up to ~200 MHz.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Optical isolation with a chiral absorber.
Fig. 2: Implementation and characterization of phonon-mediated p-ATS isolator.
Fig. 3: Experimental demonstration of phonon-mediated p-ATS isolators near 1,550 and 780 nm.
Fig. 4: Demonstration of giant isolation using dressed state non-reciprocity.

Data availability

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

Code availability

All relevant code is available from the corresponding author upon reasonable request.


  1. Hwang, I. K., Yun, S. H. & Kim, B. Y. All-fiber-optic nonreciprocal modulator. Opt. Lett. 22, 507–509 (1997).

    Article  ADS  Google Scholar 

  2. Kang, M. S., Butsch, A. & Russell, P. S. J. Reconfigurable light-driven opto-acoustic isolators in photonic crystal fibre. Nat. Photon. 5, 549–553 (2011).

    Article  ADS  Google Scholar 

  3. Doerr, C. R., Dupuis, N. & Zhang, L. Optical isolator using two tandem phase modulators. Opt. Lett. 36, 4293–4295 (2011).

    Article  ADS  Google Scholar 

  4. Lira, H., Yu, Z., Fan, S. & Lipson, M. Electrically driven nonreciprocity induced by interband photonic transition on a silicon chip. Phys. Rev. Lett. 109, 033901 (2012).

    Article  ADS  Google Scholar 

  5. Tzuang, L. D., Fang, K., Nussenzveig, P., Fan, S. & Lipson, M. Non-reciprocal phase shift induced by an effective magnetic flux for light. Nat. Photon. 8, 701–705 (2014).

    Article  Google Scholar 

  6. Li, E., Eggleton, B. J., Fang, K. & Fan, S. Photonic Aharonov–Bohm effect in photon–phonon interactions. Nat. Commun. 5, 3225 (2014).

    Article  ADS  Google Scholar 

  7. Sounas, D. L. & Alù, A. Angular-momentum-biased nanorings to realize magnetic-free integrated optical isolation. ACS Photon. 1, 198–204 (2014).

    Article  Google Scholar 

  8. Dong, C.-H. et al. Brillouin-scattering-induced transparency and non-reciprocal light storage. Nat. Commun. 6, 6193 (2015).

  9. Kim, J., Kuzyk, M. C., Han, K., Wang, H. & Bahl, G. Non-reciprocal Brillouin scattering induced transparency. Nat. Phys. 11, 275–280 (2015).

    Article  Google Scholar 

  10. Kim, J., Kim, S. & Bahl, G. Complete linear optical isolation at the microscale with ultralow loss. Sci. Rep. 7, 1647 (2017).

    Article  ADS  Google Scholar 

  11. Ruesink, F., Miri, M.-A., Alù, A. & Verhagen, E. Nonreciprocity and magnetic-free isolation based on optomechanical interactions. Nat. Commun. 7, 13662 (2016).

    Article  ADS  Google Scholar 

  12. Fang, K. et al. Generalized non-reciprocity in an optomechanical circuit via synthetic magnetism and reservoir engineering. Nat. Phys. 13, 465–471 (2017).

    Article  Google Scholar 

  13. Sohn, D. B., Kim, S. & Bahl, G. Time-reversal symmetry breaking with acoustic pumping of nanophotonic circuits. Nat. Photon. 12, 91–97 (2018).

    Article  ADS  Google Scholar 

  14. Kittlaus, E. A., Otterstrom, N. T., Kharel, P., Gertler, S. & Rakich, P. T. Non-reciprocal interband Brillouin modulation. Nat. Photon. 12, 613–619 (2018).

    Article  ADS  Google Scholar 

  15. Peterson, C. W., Kim, S., Bernhard, J. T. & Bahl, G. Synthetic phonons enable nonreciprocal coupling to arbitrary resonator networks. Sci. Adv. 4, eaat0232 (2018).

    Article  ADS  Google Scholar 

  16. Shi, Y., Lin, Q., Minkov, M. & Fan, S. Nonreciprocal optical dissipation based on direction-dependent Rabi splitting. IEEE J. Sel. Topics Quantum Electron. 24, 1–7 (2018).

  17. Sohn, D. B. & Bahl, G. Direction reconfigurable nonreciprocal acousto-optic modulator on chip. APL Photon. 4, 126103 (2019).

    Article  ADS  Google Scholar 

  18. Tian, H. et al. Hybrid integrated photonics using bulk acoustic resonators. Nat. Commun. 11, 3073 (2020).

    Article  ADS  Google Scholar 

  19. Sarabalis, C. J. et al. Acousto-optic modulation of a wavelength-scale waveguide. Optica 8, 477–483 (2021).

    Article  ADS  Google Scholar 

  20. Dostart, N., Gevorgyan, H., Onural, D. & Popović, M. Optical isolation using microring modulators. Opt. Lett. 46, 460–463 (2021).

    Article  ADS  Google Scholar 

  21. Kim, S., Sohn, D. B., Peterson, C. W. & Bahl, G. On-chip optical non-reciprocity through a synthetic Hall effect for photons. APL Photon. 6, 011301 (2021).

    Article  ADS  Google Scholar 

  22. Kittlaus, E. A. et al. Electrically driven acousto-optics and broadband non-reciprocity in silicon photonics. Nat. Photon. 15, 43–52 (2021).

    Article  ADS  Google Scholar 

  23. Peng, B., Özdemir, Ş. K., Chen, W., Nori, F. & Yang, L. What is and what is not electromagnetically induced transparency in whispering-gallery microcavities. Nat. Commun. 5, 5082 (2014).

    Article  ADS  Google Scholar 

  24. Zhang, M. et al. Electronically programmable photonic molecule. Nat. Photon. 13, 36–40 (2019).

    Article  ADS  Google Scholar 

  25. Bi, L. et al. On-chip optical isolation in monolithically integrated non-reciprocal optical resonators. Nat. Photon. 5, 758–762 (2011).

    Article  Google Scholar 

  26. Ghosh, S. et al. Ce:YIG/silicon-on-insulator waveguide optical isolator realized by adhesive bonding. Opt. Express 20, 1839–1848 (2012).

    Article  ADS  Google Scholar 

  27. Huang, D. et al. Dynamically reconfigurable integrated optical circulators. Optica 4, 23–30 (2017).

    Article  ADS  Google Scholar 

  28. Zhang, C., Dulal, P., Stadler, B. J. H. & Hutchings, D. C. Monolithically-integrated TE-mode 1D silicon-on-insulator isolators using seedlayer-free garnet. Sci. Rep. 7, 5820 (2017).

    Article  ADS  Google Scholar 

  29. Du, Q. et al. Monolithic on-chip magneto-optical isolator with 3 dB insertion loss and 40 db isolation ratio. ACS Photon. 5, 5010–5016 (2018).

    Article  Google Scholar 

  30. Zhang, Y. et al. Monolithic integration of broadband optical isolators for polarization-diverse silicon photonics. Optica 6, 473–478 (2019).

    Article  ADS  Google Scholar 

  31. Yan, W. et al. Waveguide-integrated high-performance magneto-optical isolators and circulators on silicon nitride platforms. Optica 7, 1555–1562 (2020).

    Article  ADS  Google Scholar 

  32. Maayani, S. et al. Flying couplers above spinning resonators generate irreversible refraction. Nature 558, 569–572 (2018).

    Article  ADS  Google Scholar 

  33. Scheucher, M., Hilico, A., Will, E., Volz, J. & Rauschenbeutel, A. Quantum optical circulator controlled by a single chirally coupled atom. Science 354, 1577–1580 (2016).

    Article  Google Scholar 

  34. Spencer, D. T. et al. An optical-frequency synthesizer using integrated photonics. Nature 557, 81–85 (2018).

    Article  ADS  Google Scholar 

  35. Lucas, E. et al. Ultralow-noise photonic microwave synthesis using a soliton microcomb-based transfer oscillator. Nat. Commun. 11, 374 (2020).

    Article  ADS  Google Scholar 

  36. Poulton, C. V. et al. Coherent solid-state LIDAR with silicon photonic optical phased arrays. Opt. Lett. 42, 4091–4094 (2017).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  38. Hummon, M. T. et al. Photonic chip for laser stabilization to an atomic vapor with 10−11 instability. Optica 5, 443–449 (2018).

    Article  ADS  Google Scholar 

  39. Knappe, S. et al. A microfabricated atomic clock. Appl. Phys. Lett. 85, 1460–1462 (2004).

    Article  ADS  Google Scholar 

  40. Newman, Z. L. et al. Architecture for the photonic integration of an optical atomic clock. Optica 6, 680–685 (2019).

    Article  ADS  Google Scholar 

  41. Peng, B. et al. Parity-time-symmetric whispering-gallery microcavities. Nat. Phys 10, 394–398 (2014).

    Article  Google Scholar 

  42. Gong, S. & Piazza, G. Design and analysis of lithium–niobate-based high electromechanical coupling RF-MEMS resonators for wideband filtering. IEEE Trans. Microw. Theory Techn. 61, 403–414 (2013).

  43. Riedel, M. F. et al. Atom-chip-based generation of entanglement for quantum metrology. Nature 464, 1170–1173 (2010).

    Article  ADS  Google Scholar 

  44. Blanshan, E., Rochester, S. M., Donley, E. A. & Kitching, J. Light shifts in a pulsed cold-atom coherent-population-trapping clock. Phys. Rev. A 91, 041401 (2015).

    Article  ADS  Google Scholar 

  45. Tian, H. et al. Magnetic-free silicon nitride integrated optical isolator. Preprint at (2021).

Download references


This work was sponsored by the Defense Advanced Research Projects Agency (DARPA) grant FA8650-19-2-7924, the National Science Foundation EFRI grant EFMA-1641084 and the Air Force Office of Scientific Research (AFOSR) grant FA9550-19-1-0256. G.B. additionally acknowledges support from the Office of Naval Research (ONR) Director for Research Early Career grant N00014-17-1-2209 and the Presidential Early Career Award for Scientists and Engineers. D.B.S. acknowledges support from a US National Science Foundation Graduate Research Fellowship. We also thank K. Chow at the Holonyak Micro & Nanotechnology Lab (HMNTL) at the University of Illinois for valuable advice and guidance. The US Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of DARPA or the US Government.

Author information

Authors and Affiliations



D.B.S., O.E.Ö. and G.B. jointly conceived the isolator concept. D.B.S. and O.E.Ö. performed the device fabrication, conducted the experimental measurements and analysed the data. All the authors contributed to writing the paper. G.B. supervised all aspects of this project.

Corresponding author

Correspondence to Gaurav Bahl.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review informationNature Photonics thanks Chun-Hua Dong and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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

Supplementary information

Supplementary Information

Supplementary Figs. 1–5, discussion and Tables 1 and 2.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sohn, D.B., Örsel, O.E. & Bahl, G. Electrically driven optical isolation through phonon-mediated photonic Autler–Townes splitting. Nat. Photon. 15, 822–827 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing