Open AccessSpatial distribution of electric-field enhancement across the gap of terahertz bow-tie antennas
Author(s) -
Matthias Runge,
Dieter Engel,
Michael Schneider,
K. Reimann,
M. Woerner,
Thomas Elsaesser
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.399462
Subject(s) - terahertz radiation , optics , electric field , materials science , terahertz spectroscopy and technology , antenna (radio) , terahertz gap , optoelectronics , physics , far infrared laser , telecommunications , laser , terahertz metamaterials , quantum mechanics , computer science
The electric-field enhancement in terahertz (THz) antennas designed for nonlinear THz spectroscopy of soft matter is characterized by spatially resolved electrooptic sampling. To mimic the relevant interaction geometry, metallic, resonant bow-tie antennas are deposited on a thin zinc telluride crystal of 10 µm thickness. The THz electric field transmitted through the antenna gap is recorded by electrooptic sampling. By focusing the 800 nm, sub-20 fs sampling pulses, we achieve a spatial resolution of some 3 µm, which is 1/3 to 1/8 of the antenna-gap width. The THz field in the gap displays an enhancement by a factor of up to 4.5 with a pronounced spectral variation, depending sensitively on the antenna-arm length and the gap width. By scanning the 800 nm probe spot laterally through the antenna gap, the spatial variation of the enhancement is determined, reaching the highest values at the edges of the gap. The results are in agreement with simulations of the electric-field distributions by finite-element calculations.