Ultrafast imaging of terahertz electric waveforms using quantum dots

Titelangaben

Heindl, Moritz ; Kirkwood, Nicholas ; Lauster, Tobias ; Lang, Julia ; Retsch, Markus ; Mulvaney, Paul ; Herink, Georg:
Ultrafast imaging of terahertz electric waveforms using quantum dots.
In: Light: Science & Applications. Bd. 11 (2022) . - 5.
ISSN 2047-7538
DOI: https://doi.org/10.1038/s41377-021-00693-5

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Abstract

Microscopic electric fields govern the majority of elementary excitations in condensed matter and drive electronics at
frequencies approaching the Terahertz (THz) regime. However, only few imaging schemes are able to resolve subwavelength
fields in the THz range, such as scanning-probe techniques, electro-optic sampling, and ultrafast electron
microscopy. Still, intrinsic constraints on sample geometry, acquisition speed and field strength limit their applicability.
Here, we harness the quantum-confined Stark-effect to encode ultrafast electric near-fields into colloidal quantum dot
luminescence. Our approach, termed Quantum-probe Field Microscopy (QFIM), combines far-field imaging of visible
photons with phase-resolved sampling of electric waveforms. By capturing ultrafast movies, we spatio-temporally
resolve a Terahertz resonance inside a bowtie antenna and unveil the propagation of a Terahertz waveguide excitation
deeply in the sub-wavelength regime. The demonstrated QFIM approach is compatible with strong-field excitation
and sub-micrometer resolution—introducing a direct route towards ultrafast field imaging of complex nanodevices inoperando.