Open AccessTime-resolved terahertz time-domain near-field microscopy
Author(s) -
Niels J. J. van Hoof,
Stan ter Huurne,
Jaime Gómez Rivas,
Alexei Halpin
Publication year - 2018
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.032118
Subject(s) - terahertz radiation , optics , materials science , terahertz spectroscopy and technology , microscope , terahertz time domain spectroscopy , near field scanning optical microscope , microscopy , optoelectronics , ultrashort pulse , gallium arsenide , laser , semiconductor , photoexcitation , optical microscope , excitation , physics , scanning electron microscope , quantum mechanics
We demonstrate a novel method for measuring terahertz (THz) photoconductivity of semiconductors on length scales smaller than the diffraction limit at THz frequencies. This method is based on a near-eld microscope that measures the transmission of a THz pulse through the semiconductor following photoexcitation by an ultrafast laser pulse. Combining back-excitation of the sample using a Dove prism, and a dual lock-in detection scheme, our microscope design offers a exible platform for near-eld time-resolved THz time-domain spectroscopy, using uences available to typical laser oscillators. Experimental results on a thin lm of gallium arsenide grown by metal organic chemical vapor deposition are presented as a proof-of-concept, demonstrating the ability to map the complex conductivity as well as sub-ps dynamics of photoexcited carriers with a resolution of λ/10 at 0.5 THz.