Femtosecond photo-switching of interface polaritons in black phosphorus heterostructures

  • Nature Nanotechnology 12, 207211 (2017)
  • doi:10.1038/nnano.2016.261
  • Download Citation
Published online:


The possibility of hybridizing collective electronic motion with mid-infrared light to form surface polaritons has made van der Waals layered materials a versatile platform for extreme light confinement1,2,3,4,5 and tailored nanophotonics6,7,8. Graphene9,10 and its heterostructures11,12,13,14 have attracted particular attention because the absence of an energy gap allows plasmon polaritons to be tuned continuously. Here, we introduce black phosphorus15,16,17,18,19 as a promising new material in surface polaritonics that features key advantages for ultrafast switching. Unlike graphene, black phosphorus is a van der Waals bonded semiconductor, which enables high-contrast interband excitation of electron–hole pairs by ultrashort near-infrared pulses. Here, we design a SiO2/black phosphorus/SiO2 heterostructure in which the surface phonon modes of the SiO2 layers hybridize with surface plasmon modes in black phosphorus that can be activated by photo-induced interband excitation. Within the Reststrahlen band of SiO2, the hybrid interface polariton assumes surface-phonon-like properties, with a well-defined frequency and momentum and excellent coherence. During the lifetime of the photogenerated electron–hole plasma, coherent hybrid polariton waves can be launched by a broadband mid-infrared pulse coupled to the tip of a scattering-type scanning near-field optical microscopy set-up. The scattered radiation allows us to trace the new hybrid mode in time, energy and space. We find that the surface mode can be activated within 50 fs and disappears within 5 ps, as the electron–hole pairs in black phosphorus recombine. The excellent switching contrast and switching speed, the coherence properties and the constant wavelength of this transient mode make it a promising candidate for ultrafast nanophotonic devices.

  • Subscribe to Nature Nanotechnology for full access:



Additional access options:

Already a subscriber?  Log in  now or  Register  for online access.


  1. 1.

    & Graphene plasmonics for terahertz to mid-infrared applications. ACS Nano 8, 1086–1101 (2014).

  2. 2.

    et al. Gate-tuning of graphene plasmons revealed by infrared nano-imaging. Nature 487, 82–85 (2012).

  3. 3.

    et al. Optical nano-imaging of gate-tunable graphene plasmons. Nature 487, 77–81 (2012).

  4. 4.

    et al. Infrared nanoscopy of Dirac plasmons at the graphene–SiO2 interface. Nano Lett. 11, 4701–4705 (2011).

  5. 5.

    et al. Tunable phonon polaritons in atomically thin van der Waals crystals of boron nitride. Science 343, 1125–1129 (2014).

  6. 6.

    et al. Atomic-scale photonic hybrids for mid-infrared and terahertz nanophotonics. Nat. Nanotech. 11, 9–15 (2016).

  7. 7.

    et al. Plasmonics for extreme light concentration and manipulation. Nat. Mater. 9, 193–204 (2010).

  8. 8.

    , , , & Two-dimensional material nanophotonics. Nat. Photon. 8, 899–907 (2014).

  9. 9.

    et al. Ultrafast and nanoscale plasmonic phenomena in exfoliated graphene revealed by infrared pump–probe nanoscopy. Nano Lett. 14, 894–900 (2014).

  10. 10.

    et al. Ultrafast optical switching of infrared plasmon polaritons in high-mobility graphene. Nat. Photon. 10, 244–247 (2016).

  11. 11.

    & Van der Waals heterostructures. Nature 499, 419–425 (2013).

  12. 12.

    et al. Highly confined low-loss plasmons in graphene–boron nitride heterostructures. Nat. Mater. 14, 421–425 (2014).

  13. 13.

    et al. Hybrid surface-phonon–plasmon polariton modes in graphene/monolayer h-BN heterostructures. Nano Lett. 14, 3876–3880 (2014).

  14. 14.

    et al. Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial. Nat. Nanotech. 10, 682–686 (2015).

  15. 15.

    , , , & The renaissance of black phosphorus. Proc. Natl Acad. Sci. USA 112, 4523–4530 (2015).

  16. 16.

    , , , & High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus. Nat. Commun. 5, 4475 (2014).

  17. 17.

    et al. Black phosphorus field-effect transistors. Nat. Nanotech. 9, 372–377 (2014).

  18. 18.

    et al. Black phosphorus terahertz photodetectors. Adv. Mater. 27, 5567–5572 (2015).

  19. 19.

    et al. Efficient terahertz detection in black-phosphorus nano-transistors with selective and controllable plasma-wave, bolometric and thermoelectric response. Sci. Rep. 6, 20474 (2016).

  20. 20.

    et al. Isolation and characterization of few-layer black phosphorus. 2D Mater. 1, 025001 (2014).

  21. 21.

    et al. Nanoscopy of black phosphorus degradation. Adv. Mater. Interfaces 3, 1600121 (2016).

  22. 22.

    et al. Effective passivation of exfoliated black phosphorus transistors against ambient degradation. Nano Lett. 14, 6964–6970 (2014).

  23. 23.

    et al. Transport properties of pristine few-layer black phosphorus by van der Waals passivation in an inert atmosphere. Nat. Commun. 6, 6647 (2015).

  24. 24.

    et al. Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution. Nat. Photon. 8, 841–845 (2014).

  25. 25.

    et al. Ultrafast mid-infrared nanoscopy of strained vanadium dioxide nanobeams. Nano Lett. 16, 1421–1427 (2016).

  26. 26.

    et al. Plasmonic superlensing in doped GaAs. Nano Lett. 15, 1057–1061 (2015).

  27. 27.

    et al. Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material. Nat. Mater. 15, 870–875 (2016).

  28. 28.

    & Electro-optic detection of subwavelength terahertz spot sizes in the near field of a metal tip. Appl. Phys. Lett. 81, 1558–1560 (2002).

  29. 29.

    et al. Sub-cycle switch-on of ultrastrong light–matter interaction. Nature 458, 178–181 (2009).

  30. 30.

    et al. Two-dimensional atomic crystals. Proc. Natl Acad. Sci. USA 102, 10451–10453 (2005).

Download references


The authors thank M. Furthmeier for technical assistance and A. Politano, S.I. Blanter, A. Chernikov, D. Peller, and M. Eisele for discussions. This work was supported by the European Research Council through ERC grant 305003 (QUANTUMsubCYCLE) and ERC grant 681379 (SPRINT), the Deutsche Forschungsgemeinschaft through Research Training Group GRK 1570, SFB 689 and research grants CO1492/1 and HU1598/3.

Author information


  1. Department of Physics, University of Regensburg, 93040 Regensburg, Germany

    • Markus A. Huber
    • , Fabian Mooshammer
    • , Markus Plankl
    • , Fabian Sandner
    • , Lukas Z. Kastner
    • , Tobias Frank
    • , Jaroslav Fabian
    • , Tyler L. Cocker
    •  & Rupert Huber
  2. NEST, CNR – Istituto Nanoscienze and Scuola Normale Superiore, 56127 Pisa, Italy

    • Leonardo Viti
    •  & Miriam S. Vitiello


  1. Search for Markus A. Huber in:

  2. Search for Fabian Mooshammer in:

  3. Search for Markus Plankl in:

  4. Search for Leonardo Viti in:

  5. Search for Fabian Sandner in:

  6. Search for Lukas Z. Kastner in:

  7. Search for Tobias Frank in:

  8. Search for Jaroslav Fabian in:

  9. Search for Miriam S. Vitiello in:

  10. Search for Tyler L. Cocker in:

  11. Search for Rupert Huber in:


M.A.H., M.S.V., T.L.C. and R.H. conceived the study. M.A.H., F.M., M.P., F.S., L.Z.K., T.L.C. and R.H. carried out the experiment and analysed the data. L.V. and M.S.V. designed, fabricated and characterized the heterostructures of black phosphorus and silicon dioxide. M.A.H., F.M., M.P., T.F. and J.F. performed simulations. M.A.H., F.M., M.S.V., T.L.C. and R.H. wrote the manuscript. All authors contributed to the discussions.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Miriam S. Vitiello or Tyler L. Cocker.

Supplementary information

PDF files

  1. 1.

    Supplementary information

    Supplementary information