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.

Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution


Phase-locked ultrashort pulses in the rich terahertz spectral range1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18 have provided key insights into phenomena as diverse as quantum confinement7, first-order phase transitions8,12, high-temperature superconductivity11 and carrier transport in nanomaterials1,6,13,14,15. Ultrabroadband electro-optic sampling of few-cycle field transients1 can even reveal novel dynamics that occur faster than a single oscillation cycle of light4,8,10. However, conventional terahertz spectroscopy is intrinsically restricted to ensemble measurements by the diffraction limit. As a result, it measures dielectric functions averaged over the size, structure, orientation and density of nanoparticles, nanocrystals or nanodomains. Here, we extend ultrabroadband time-resolved terahertz spectroscopy to the sub-nanoparticle scale (10 nm) by combining sub-cycle, field-resolved detection (10 fs) with scattering-type near-field scanning optical microscopy (s-NSOM)16,17,18,19,20,21,22,23,24,25,26. We trace the time-dependent dielectric function at the surface of a single photoexcited InAs nanowire in all three spatial dimensions and reveal the ultrafast (<50 fs) formation of a local carrier depletion layer.

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

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Set-up for single-nanowire terahertz spectroscopy.
Figure 2: Dynamics of the oscillating electric near field.
Figure 3: Sub-cycle spectral dynamics.
Figure 4: Femtosecond tomography.


  1. Ulbricht, R., Hendry, E., Shan, J., Heinz, T. F. & Bonn, M. Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy. Rev. Mod. Phys. 83, 543–586 (2011).

  2. Kampfrath, T., Tanaka, K. & Nelson, K. A. Resonant and nonresonant control over matter and light by intense terahertz transients. Nature Photon. 7, 680–690 (2013).

    Article  ADS  Google Scholar 

  3. Kindt, J. T. & Schmuttenmaer, C. A. Theory for determination of the low- frequency time-dependent response function in liquids using time-resolved terahertz pulse spectroscopy. J. Chem. Phys. 110, 8589–8596 (1999).

    Article  ADS  Google Scholar 

  4. Huber, R. et al. How many-particle interactions develop after ultrafast excitation of an electron–hole plasma. Nature 414, 286–289 (2001).

    Article  ADS  Google Scholar 

  5. Kaindl, R. A., Carnahan, M. A., Hägele, D., Lövenich, R. & Chemla, D. S. Ultrafast terahertz probes of transient conducting and insulating phases in an electron–hole gas. Nature 423, 734–738 (2003).

    Article  ADS  Google Scholar 

  6. Baxter, J. B. & Schmuttenmaer, C. A. Conductivity of ZnO nanowires, nanoparticles, and thin films using time-resolved terahertz spectroscopy. J. Phys. Chem. B 110, 25229–25239 (2006).

    Article  Google Scholar 

  7. Wang, F. et al. Exciton polarizability in semiconductor nanocrystals. Nature Mater. 5, 861–864 (2006).

    Article  ADS  Google Scholar 

  8. Kübler, C. et al. Coherent structural dynamics and electronic correlations during an ultrafast insulator-to-metal phase transition in VO2 . Phys. Rev. Lett. 99, 116401 (2007).

    Article  ADS  Google Scholar 

  9. Gaal, P. et al. Internal motions of a quasiparticle governing its ultrafast nonlinear response. Nature 450, 1210–1213 (2007).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  11. Pashkin, A. et al. Femtosecond response of quasiparticles and phonons in superconducting YBa2Cu3O7−δ studied by wideband terahertz spectroscopy. Phys. Rev. Lett. 105, 067001 (2010).

    Article  ADS  Google Scholar 

  12. Liu, M. K. et al. Photoinduced phase transitions by time-resolved far-infrared spectroscopy in V2O3 . Phys. Rev. Lett. 107, 066403 (2011).

  13. Seletskiy, D. V. et al. Efficient terahertz emission from InAs nanowires. Phys. Rev. B 84, 115421 (2011).

    Article  ADS  Google Scholar 

  14. Joyce, H. J. et al. Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy. Nanotechnology 24, 214006 (2013).

    Article  ADS  Google Scholar 

  15. Cocker, T. L. et al. An ultrafast terahertz scanning tunnelling microscope. Nature Photon. 7, 620–625 (2013).

    Article  ADS  Google Scholar 

  16. Chen, H.-T., Kersting, R. & Cho, G. C. Terahertz imaging with nanometer resolution. Appl. Phys. Lett. 83, 3009–3011 (2003).

    Article  ADS  Google Scholar 

  17. Zhan, H. et al. The metal–insulator transition in VO2 studied using terahertz apertureless near-field microscopy. Appl. Phys. Lett. 91, 162110 (2007).

    Article  ADS  Google Scholar 

  18. Moon, K. et al. Quantitative coherent scattering spectra in apertureless terahertz pulse near-field microscopes. Appl. Phys. Lett. 101, 011109 (2012).

    Article  ADS  Google Scholar 

  19. Krutokhvostov, R. et al. Enhanced resolution in subsurface near-field optical microscopy. Opt. Express 20, 593–600 (2012).

    Article  ADS  Google Scholar 

  20. Qazilbash, M. M. et al. Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging. Science 318, 1750–1753 (2007).

    Article  ADS  Google Scholar 

  21. Jones, A. C. et al. Mid-IR plasmonics: near-field imaging of coherent plasmon modes of silver nanowires. Nano Lett. 9, 2553–2558 (2009).

    Article  ADS  Google Scholar 

  22. Diyar, S. et al. Adiabatic nanofocusing scattering-type optical nanoscopy of individual gold nanoparticles. Nano Lett. 11, 1609–1613 (2011).

    Article  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  25. Jacob, R. et al. Intersublevel spectroscopy on single InAs-quantum dots by terahertz near-field microscopy. Nano Lett. 12, 4336–4340 (2012).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  27. Vitiello, M. S. et al. Room-temperature terahertz detectors based on semiconductor nanowire field-effect transistors. Nano Lett. 12, 96–101 (2012).

    Article  ADS  Google Scholar 

  28. Saxena, D. et al. Optically pumped room-temperature GaAs nanowire lasers. Nature Photon. 7, 963–968 (2013).

    Article  ADS  Google Scholar 

  29. Mayer, B. et al. Lasing from individual GaAs–AlGaAs core–shell nanowires up to room temperature. Nature Commun. 4, 2931 (2013).

    Article  ADS  Google Scholar 

  30. Krauss, G. et al. Synthesis of a single cycle of light with compact erbium-doped fibre technology. Nature Photon. 4, 33–36 (2010).

    Article  ADS  Google Scholar 

  31. Piper, L. F. J., Veal, T. D., Lowe, M. J. & McConville, C. F. Electron depletion at InAs free surfaces: doping-induced acceptorlike gap states. Phys. Rev. B 73, 195321 (2006).

    Article  ADS  Google Scholar 

  32. Dekorsy, T., Pfeifer, T., Kütt, W. & Kurz, H. Subpicosecond carrier transport in GaAs surface-space-charge fields. Phys. Rev. B 47, 3842–3849 (1993).

    Article  ADS  Google Scholar 

Download references


The authors thank M. Furthmeier for technical assistance and J. Lupton, P. Klemm, D. Bougeard, B. Surrer, R. Hillenbrand and F. Keilmann for discussions. This work was supported by the European Research Council through ERC grant 305003 (QUANTUMsubCYCLE), the Deutsche Forschungsgemeinschaft through Graduate Research College GRK 1570, and the Italian Ministry of Education, University, and Research (MIUR) through the Futuro in Ricerca 2010 grant RBFR10LULP (Fundamental Research on Terahertz Photonic Devices). T.L.C. acknowledges the support of the Alexander von Humboldt Foundation.

Author information

Authors and Affiliations



M.E., T.L.C. and R.H. conceived the study and built the experimental set-up. M.E., T.L.C., M.A.H., M.P. and R.H. carried out the experiment and analysed the data. M.A.H., T.L.C. and M.E. performed simulations. D.E. and L.S. grew the InAs nanowires. L.V. and M.S.V. designed, fabricated and characterized the nanowire samples. T.L.C., M.E., M.A.H. and R.H. wrote the manuscript. All authors contributed to the discussions.

Corresponding author

Correspondence to R. Huber.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 2283 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Eisele, M., Cocker, T., Huber, M. et al. Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution. Nature Photon 8, 841–845 (2014).

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