Exciton resonance tuning of an atomically thin lens


The highly engineerable scattering properties of resonant optical antennas underpin the operation of metasurface-based flat optics. Thus far, the choice of antenna has been limited to shaped metallic and high-index semiconductor nanostructures that support geometrical plasmonic or Mie resonances. Whereas these resonant elements offer strong light–matter interaction and excellent control over the scattering phase and amplitude, their electrical tunability has proven to be quite limited. Here, we demonstrate how excitonic resonances in atomically thin semiconductors can be harnessed as a different, third type of resonance to create mutable, flat optics. These strong materials-based resonances are unmatched in their tunability with various external stimuli. To illustrate the concept, we first demonstrate how excitons can enhance the focusing efficiency of a millimetre-scale, patterned WS2 zone plate lens. We also show how electrical gating can completely turn on and off the exciton resonance and thereby modulate the focusing efficiency by 33%.

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Fig. 1: Atomically thin and tunable flat lenses.
Fig. 2: Material susceptibility and focusing efficiency.
Fig. 3: Exciton manipulation through ionic-liquid gating.
Fig. 4: Exciton modulation of the intensity in the focus.

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.


  1. 1.

    Lalanne, P. & Chavel, P. Metalenses at visible wavelengths: past, present, perspectives. Laser Photon. Rev. 11, 1600295 (2017).

  2. 2.

    Chen, H. T., Taylor, A. J. & Yu, N. A review of metasurfaces: physics and applications. Rep. Prog. Phys. 79, 076401 (2016).

  3. 3.

    Khorasaninejad, M. & Capasso, F. Metalenses: versatile multifunctional photonic components. Science 358, eaam8100 (2017).

  4. 4.

    Yu, N. et al. Light propagation with phase discontinuities: generalized laws of reflection and refraction. Science 334, 333–337 (2011).

  5. 5.

    Lin, D., Fan, P., Hasman, E. & Brongersma, M. L. Dielectric gradient metasurface optical elements. Science 345, 298–302 (2014).

  6. 6.

    Kamali, S. M. et al. Angle-multiplexed metasurfaces: encoding independent wavefronts in a single metasurface under different illumination angles. Phys. Rev. X 7, 041056 (2017).

  7. 7.

    Maguid, E. et al. Multifunctional interleaved geometric-phase dielectric metasurfaces. Light Sci. Appl. 6, e17027 (2017).

  8. 8.

    Paniagua-Domínguez, R. et al. A metalens with a near-unity numerical aperture. Nano Lett. 18, 2124–2132 (2018).

  9. 9.

    Liang, H. et al. Ultrahigh numerical aperture metalens at visible wavelengths. Nano Lett. 18, 4460–4466 (2018).

  10. 10.

    Khorasaninejad, M. et al. Metalenses at visible wavelengths: diffraction-limited focusing and subwavelength resolution imaging. Science 352, 1190–1194 (2016).

  11. 11.

    Shrestha, S., Overvig, A. C., Lu, M., Stein, A. & Yu, N. Broadband achromatic dielectric metalenses. Light Sci. Appl. 7, 85 (2018).

  12. 12.

    Wang, S. et al. A broadband achromatic metalens in the visible. Nat. Nanotechnol. 13, 227–232 (2018).

  13. 13.

    Li, G., Zhang, S. & Zentgraf, T. Nonlinear photonic metasurfaces. Nat. Rev. Mater. 2, 17010 (2017).

  14. 14.

    Krasnok, A., Tymchenko, M. & Alù, A. Nonlinear metasurfaces: a paradigm shift in nonlinear optics. Mater. Today 21, 8–21 (2018).

  15. 15.

    Lin, R. J. et al. Achromatic metalens array for full-colour light-field imaging. Nat. Nanotechnol. 14, 227–231 (2019).

  16. 16.

    Holsteen, A. L., Lin, D., Kauvar, I., Wetzstein, G. & Brongersma, M. L. A light-field metasurface for high-resolution single-particle tracking. Nano Lett. 19, 2267–2271 (2019).

  17. 17.

    Schwarz, B. LIDAR: mapping the world in 3D. Nat. Photon. 4, 429–430 (2010).

  18. 18.

    Jung, I. W. et al. 2-D MEMS scanner for handheld multispectral confocal microscopes. In 2012 Int. Conf. on Optical MEMS and Nanophotonics 238–239 (IEEE, 2012).

  19. 19.

    Miller, D. A. B. Attojoule optoelectronics for low-energy information processing and communications. J. Light. Technol. 35, 346–396 (2017).

  20. 20.

    Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).

  21. 21.

    Cao, L. Two-dimensional transition-metal dichalcogenide materials: toward an age of atomic-scale photonics. Mater. Res. Soc. Bull. 40, 592–599 (2015).

  22. 22.

    Stier, A. V., Wilson, N. P., Clark, G., Xu, X. & Crooker, S. A. Probing the influence of dielectric environment on excitons in monolayer WSe2: insight from high magnetic fields. Nano Lett. 16, 7054–7060 (2016).

  23. 23.

    Raja, A. et al. Coulomb engineering of the bandgap and excitons in two-dimensional materials. Nat. Commun. 8, 15251 (2017).

  24. 24.

    Gupta, G., Kallatt, S. & Majumdar, K. Direct observation of giant binding energy modulation of exciton complexes in monolayer MoSe2. Phys. Rev. B 96, 081403 (2017).

  25. 25.

    Stier, A. V. et al. Magnetooptics of exciton Rydberg states in a monolayer semiconductor. Phys. Rev. Lett. 120, 057405 (2018).

  26. 26.

    Lloyd, D. et al. Band gap engineering with ultralarge biaxial strains in suspended monolayer MoS2. Nano Lett. 16, 5836–5841 (2016).

  27. 27.

    Aslan, O. B., Deng, M. & Heinz, T. F. Strain tuning of excitons in monolayer WSe2. Phys. Rev. B 98, 115308 (2018).

  28. 28.

    Ross, J. S. et al. Electrical control of neutral and charged excitons in a monolayer semiconductor. Nat. Commun. 4, 1474 (2013).

  29. 29.

    Chernikov, A. et al. Electrical tuning of exciton binding energies in monolayer WS2. Phys. Rev. Lett. 115, 126802 (2015).

  30. 30.

    Yu, Y. et al. Giant gating tunability of optical refractive index in transition metal dichalcogenide monolayers. Nano Lett. 17, 3613–3618 (2017).

  31. 31.

    Mak, K. F. & Shan, J. Mirrors made of a single atomic layer. Nature 556, 177–178 (2018).

  32. 32.

    Back, P., Zeytinoglu, S., Ijaz, A., Kroner, M. & Imamoǧlu, A. Realization of an electrically tunable narrow-bandwidth atomically thin mirror using monolayer MoSe2. Phys. Rev. Lett. 120, 037401 (2018).

  33. 33.

    Scuri, G. et al. Large excitonic reflectivity of monolayer MoSe2 encapsulated in hexagonal boron nitride. Phys. Rev. Lett. 120, 037402 (2018).

  34. 34.

    Krasnok, A., Lepeshov, S. & Alú, A. Nanophotonics with 2D transition metal dichalcogenides. Opt. Express 26, 15972–15994 (2018).

  35. 35.

    Tserkezis, C. et al. Mie excitons: understanding strong coupling in dielectric nanoparticles. Phys. Rev. B 98, 155439 (2018).

  36. 36.

    Yang, J. et al. Atomically thin optical lenses and gratings. Light Sci. Appl. 5, e16046 (2016).

  37. 37.

    Liu, C. H. et al. Ultrathin van der Waals metalenses. Nano Lett. 18, 6961–6966 (2018).

  38. 38.

    Kong, X. T. et al. Graphene-based ultrathin flat lenses. ACS Photon. 2, 200–207 (2015).

  39. 39.

    Zheng, X. et al. Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing. Nat. Commun. 6, 8433 (2015).

  40. 40.

    Lin, H., Xu, Z. Q., Qiu, C., Jia, B. & Bao, Q. High performance atomically thin flat lenses. Preprint at https://arxiv.org/abs/1611.06457 (2016).

  41. 41.

    Georgiou, T. et al. Vertical field-effect transistor based on graphene–WS2 heterostructures for flexible and transparent electronics. Nat. Nanotechnol. 8, 100–103 (2012).

  42. 42.

    Shealy, D. L. & Hoffnagle, J. A. Laser beam shaping profiles and propagation. Appl. Opt. 45, 5118–5131 (2006).

  43. 43.

    Li, Y. et al. Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS2, MoSe2, WS2, and WSe2. Phys. Rev. B 90, 205422 (2014).

  44. 44.

    Li, Q. T. et al. Free-space optical beam tapping with an all-silica metasurface. ACS Photon. 4, 2544–2549 (2017).

  45. 45.

    Lien, D. H. et al. Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors. Science 364, 468–471 (2019).

  46. 46.

    Leighton, C. Electrolyte-based ionic control of functional oxides. Nat. Mater. 18, 13–18 (2019).

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We gratefully acknowledge useful discussions with M. Gebbie. This work was supported by the US Air Force (grant no. AnchorFA9550-17-1-0331). Some of the optical measurements were funded by the DOE ‘Photonics at Thermodynamic Limits’ Energy Frontier Research Center under grant DE-SC0019140. J.v.d.G. was also supported by a Rubicon Fellowship from the ‘Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)’. J.-H.S. was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1A6A3A03012480). U.C. acknowledges the partial support from the Fonds voor Wetenschappelijk Onderzoek—Vlaanderen (FWO). Part of this work was performed at the Nano@Stanford labs, supported by the National Science Foundation under award ECCS-1542152.

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J.v.d.G. and M.L.B. conceived the concepts behind this research. J.v.d.G. and J.-H.S. fabricated the samples and performed the optical measurements. U.C. performed the (conductive) AFM measurements. J.v.d.G., J.-H.S., Q.L., P.G.K. and M.L.B. performed the data analysis and calculations. All authors contributed to writing the manuscript.

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Correspondence to Mark L. Brongersma.

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Supplementary Figs. 1–11 and Notes 1 and 2.

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van de Groep, J., Song, J., Celano, U. et al. Exciton resonance tuning of an atomically thin lens. Nat. Photonics (2020). https://doi.org/10.1038/s41566-020-0624-y

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