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arXiv · 1604.04304

Ultrafast single-nanowire multi-terahertz spectroscopy with sub-cycle temporal resolution

M. Eisele·T. L. Cocker·M. A. Huber·M. Plankl·L. Viti·D. Ercolani·L. Sorba·M. S. Vitiello·R. Huber
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Abstract

Phase-locked ultrashort pulses in the rich terahertz (THz) spectral range have provided key insights into phenomena as diverse as quantum confinement, first-order phase transitions, high-temperature superconductivity, and carrier transport in nanomaterials. Ultrabroadband electro-optic sampling of few-cycle field transients can even reveal novel dynamics that occur faster than a single oscillation cycle of light. However, conventional THz 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 THz spectroscopy (20 - 50 THz) 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). 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.

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M. Eisele, T. L. Cocker, M. A. Huber, M. Plankl, L. Viti, D. Ercolani, L. Sorba, M. S. Vitiello, R. Huber. 2016-04-14. Ultrafast single-nanowire multi-terahertz spectroscopy with sub-cycle temporal resolution. https://doi.org/10.1038/nphoton.2014.225

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