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Spintronic emitters for super-resolution in THz-spectral imaging
- We investigate local THz field generation using spintronic THz emitters to enhance the resolution for micrometer-sized imaging. Far-field imaging with wavelengths above 100 µm limits the resolution to this order of magnitude. By using optical laser pulses as a pump, THz field generation can be confined to the area of laser beam focusing. The divergence of the generated THz beam due to laser beam focusing requires the imaged object to be close to the generation spot at a distance below the THz field wavelength. We generate THz-radiation by fs-laser pulses in CoFeB/Pt heterostructures, based on spin currents, and detect them by commercial low-temperature grown-GaAs (LT-GaAs) Auston switches. The spatial resolution of THz radiation is determined by applying a 2D scanning technique with motorized stages allowing step sizes in the sub-micrometer range. Within the near-field limit, we achieve spatial resolution in the dimensions of the laser spot size on the micrometer scale. For this purpose, a gold test pattern is evaporated on the spintronic emitter separated by a 300 nm SiO2 spacer layer. Moving these structures with respect to the femtosecond laser spot, which generates THz radiation, allows for resolution determination. The knife-edge method yields a full-width half-maximum beam diameter of 4.9 +- 0.4 µm at 1 THz. The possibility to deposit spintronic emitter heterostructures on simple glass substrates makes them attractive candidates for near-field imaging in many imaging applications.
Author: | Finn-Frederik Stiewe, Tristan Winkel, Yuta Sasaki, Tobias Tubandt, Tobias Kleinke, Christian Denker, Ulrike Martens, Nina Meyer, Tahereh Sadat Parvini, Shigemi Mizukami, Jakob Walowski, Markus Münzenberg |
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URN: | urn:nbn:de:gbv:9-opus-107614 |
DOI: | https://doi.org/10.1063/5.0076880 |
ISSN: | 1077-3118 |
Parent Title (English): | Applied Physics Letters |
Publisher: | AIP Publishing |
Place of publication: | Melville, NY |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2022/01/20 |
Date of first Publication: | 2022/01/17 |
Release Date: | 2024/02/27 |
Tag: | Cells; Femtosecond lasers; Gaussian beam; Glass; Heterostructures; Signal-to-noise ratio; Spectral imaging; Spintronic devices; Terahertz radiation; Terahertz spectroscopy |
Volume: | 120 |
Issue: | 3 |
Article Number: | 032406 |
Page Number: | 8 |
Faculties: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik |
Collections: | weitere DFG-förderfähige Artikel |
Licence (German): | Creative Commons - Namensnennung 4.0 International |