Nanoscale Laser Terahertz Emission Microscopy

Pernille Klarskov, Hyewon Kim, Vicki L. Colvin, Daniel M. Mittleman

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight into the physics of charge transport, built-in fields, grain boundaries or surface states. We describe a new implementation of LTEM with a spatial resolution in the nanoscale regime based on a scattering-type near-field tip-based approach. We observe a spectral reshaping of the signal compared to conventional LTEM, which is analyzed using a resonant antenna model. Our experimental and computational results clarify the importance of the mechanisms for both the plasmonic in-coupling of the near-infrared pulses into the near field and the out-coupling of the generated terahertz pulses. We demonstrate a tip-size-limited spatial resolution of ∼20 nm by imaging a gold nanorod using terahertz emission from the underlying substrate. This work enables for the first time the possibility of performing LTEM measurements on individual nanostructures.
Original languageEnglish
JournalA C S Photonics
Number of pages5
ISSN2330-4022
DOIs
Publication statusPublished - 2017

Keywords

  • Terahertz emission microscopy
  • Near-field imaging
  • Apertureless NSOM
  • Nonlinear optics

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