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.

Room-temperature polaritonic non-Hermitian system with single microcavity


Parity–time reversal symmetry (PT symmetry) in non-Hermitian systems realizes spontaneous symmetry breaking, thereby leading to counterintuitive phenomena. A coupled system with antisymmetric gain/loss profiles is required to introduce PT symmetry into photonics. As photons are intrinsically non-interactive, selection of two-photonic components is inevitable to mediate indirect coupling via near-fields. Remarkably, exciton–polaritons (the hybrid nature of excitons and photons) are directly interactive via excitonic components; however, the features of direct coupling between exciton–polariton modes have not been investigated so far. Here we demonstrate that such direct coupling can remodel conventional photonic platforms of non-Hermitian systems into polaritonic platforms with a single component; thus improving the degrees of freedom of both integration and design for the coupled system. We focused on the sixfold-symmetric microcavity to exploit degenerated photonic modes. By employing direct coupling with loss modulation, we observed room-temperature polaritonic PT symmetry with a phase transition from unbroken to broken, revealing the lowest threshold of polariton condensates in non-Hermitian degeneracies despite increasing loss.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Polaritonic non-Hermitian system based on hexagonal microcavity.
Fig. 2: Design and fabrication of loss control for tri-polaritons.
Fig. 3: Loss dependency of coupled tri-polariton pair.
Fig. 4: Threshold of the room-temperature polariton condensation of the coupled tri-polariton pair.
Fig. 5: Observation of polaritonic non-Hermitian degeneracies.

Data availability

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


  1. 1.

    Livio, M. Physics: why symmetry matters. Nature 490, 472–473 (2012).

    ADS  Article  Google Scholar 

  2. 2.

    Peng, B. et al. Loss-induced suppression and revival of lasing. Science 346, 328–332 (2014).

    ADS  Article  Google Scholar 

  3. 3.

    Feng, L., Wong, Z. J., Ma, R.-M., Wang, Y. & Zhang, X. Single-mode laser by parity-time symmetry breaking. Science 346, 972–975 (2014).

    ADS  Article  Google Scholar 

  4. 4.

    Hodaei, H., Miri, M.-A., Heinrich, M., Christodoulides, D. N. & Khajavikhan, M. Parity-time–symmetric microring lasers. Science 346, 975–978 (2014).

    ADS  Article  Google Scholar 

  5. 5.

    Miao, P. et al. Orbital angular momentum microlaser. Science 353, 464–467 (2016).

    ADS  Article  Google Scholar 

  6. 6.

    Peng, B. et al. Chiral modes and directional lasing at exceptional points. Proc. Natl Acad. Sci. USA 113, 6845–6850 (2016).

    ADS  Article  Google Scholar 

  7. 7.

    Lin, Z. et al. Unidirectional invisibility induced by PT-symmetric periodic structures. Phys. Rev. Lett. 106, 213901 (2011).

    ADS  Article  Google Scholar 

  8. 8.

    Feng, L. et al. Experimental demonstration of a unidirectional reflectionless parity-time metamaterial at optical frequencies. Nat. Mater. 12, 108–113 (2013).

    ADS  Article  Google Scholar 

  9. 9.

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

    Article  Google Scholar 

  10. 10.

    Chang, L. et al. Parity–time symmetry and variable optical isolation in active–passive-coupled microresonators. Nat. Photon. 8, 524–529 (2014).

    ADS  Article  Google Scholar 

  11. 11.

    Yoon, J. W. et al. Time-asymmetric loop around an exceptional point over the full optical communications band. Nature 562, 86–90 (2018).

    ADS  Article  Google Scholar 

  12. 12.

    Guo, A. et al. Observation of PT-symmetry breaking in complex optical potentials. Phys. Rev. Lett. 103, 093902 (2009).

    ADS  Article  Google Scholar 

  13. 13.

    Rüter, C. E. et al. Observation of parity–time symmetry in optics. Nat. Phys. 6, 192–195 (2010).

    Article  Google Scholar 

  14. 14.

    Benisty, H. et al. Implementation of PT symmetric devices using plasmonics: principle and applications. Opt. Exp. 19, 18004–18019 (2011).

    ADS  Article  Google Scholar 

  15. 15.

    Alaeian, H. & Dionne, J. A. Parity-time-symmetric plasmonic metamaterials. Phys. Rev. A 89, 033829 (2014).

    ADS  Article  Google Scholar 

  16. 16.

    Fleury, R., Sounas, D. L. & Alu, A. Negative refraction and planar focusing based on parity-time symmetric metasurfaces. Phys. Rev. Lett. 113, 023903 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Sun, Y., Tan, W., Li, H.-q, Li, J. & Chen, H. Experimental demonstration of a coherent perfect absorber with PT phase transition. Phys. Rev. Lett. 112, 143903 (2014).

    ADS  Article  Google Scholar 

  18. 18.

    Zhen, B. et al. Spawning rings of exceptional points out of Dirac cones. Nature 525, 354–358 (2015).

    ADS  Article  Google Scholar 

  19. 19.

    Cerjan, A., Raman, A. & Fan, S. Exceptional contours and band structure design in parity-time symmetric photonic crystals. Phys. Rev. Lett. 116, 203902 (2016).

    ADS  Article  Google Scholar 

  20. 20.

    Kim, K. H. et al. Direct observation of exceptional points in coupled photonic-crystal lasers with asymmetric optical gains. Nat. Commun. 7, 13893 (2016).

    ADS  Article  Google Scholar 

  21. 21.

    Makris, K. G., El-Ganainy, R., Christodoulides, D. & Musslimani, Z. H. Beam dynamics in PT symmetric optical lattices. Phys. Rev. Lett. 100, 103904 (2008).

    ADS  Article  Google Scholar 

  22. 22.

    Hodaei, H. et al. Enhanced sensitivity at higher-order exceptional points. Nature 548, 187–191 (2017).

    ADS  Article  Google Scholar 

  23. 23.

    Kasprzak, J. et al. Bose–Einstein condensation of exciton polaritons. Nature 443, 409–414 (2006).

    ADS  Article  Google Scholar 

  24. 24.

    Deng, H., Weihs, G., Santori, C., Bloch, J. & Yamamoto, Y. Condensation of semiconductor microcavity exciton polaritons. Science 298, 199–202 (2002).

    ADS  Article  Google Scholar 

  25. 25.

    Gao, T. et al. Observation of non-Hermitian degeneracies in a chaotic exciton–polariton billiard. Nature 526, 554–558 (2015).

    ADS  Article  Google Scholar 

  26. 26.

    Gao, T. et al. Chiral modes at exceptional points in exciton–polariton quantum fluids. Phys. Rev. Lett. 120, 065301 (2018).

    ADS  Article  Google Scholar 

  27. 27.

    Deng, H., Haug, H. & Yamamoto, Y. Exciton–polariton Bose–Einstein condensation. Rev. Mod. Phys. 82, 1489–1537 (2010).

    ADS  Article  Google Scholar 

  28. 28.

    Guillet, T. & Brimont, C. Polariton condensates at room temperature. C. R. Phys. 17, 946–956 (2016).

    ADS  Article  Google Scholar 

  29. 29.

    Song, H. G. et al. Tailoring the potential landscape of room-temperature single-mode whispering gallery polariton condensate. Optica 6, 1313–1320 (2019).

    ADS  Article  Google Scholar 

  30. 30.

    Dhruv, S. et al. Mode profiling of semiconductor nanowire lasers. Nano Lett. 15, 5342–5348 (2015).

    Article  Google Scholar 

Download references


We thank LG Innotek for providing the wire samples. This work was supported by the National Research Foundation (grant nos. 2019R1A2B5B03070642 and 2020M3E4A1080112) of the Korean government, and the Samsung Science and Technology Foundation under project no. SSTF-BA1602-05.

Author information




Y.-H.C. and H.G.S. initiated the study and designed all experiments. K.Y.W. and M.C. fabricated the engineered substrate. H.G.S. and Y.-H.C. performed optical characterizations and numerical simulations. H.G.S. and C.H.P. analysed and interpreted the experimental data. Y.-H.C. conceived and supervised this project. H.G.S and Y.-H.C wrote the manuscript, supported by all co-authors.

Corresponding author

Correspondence to Yong-Hoon Cho.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Photonics thanks Zheng Sun 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. 1–7, Table 1 and Discussion.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Song, H.G., Choi, M., Woo, K.Y. et al. Room-temperature polaritonic non-Hermitian system with single microcavity. Nat. Photon. 15, 582–587 (2021).

Download citation


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