TY  - JOUR
Y1  - 2024/03/11/
A1  - Seddon, James
A1  - Hale, Lucy
A1  - Jung, Hyunseung
A1  - Norman, Sarah
A1  - Brener, Igal
A1  - Seeds, Alwyn
A1  - Renaud, Cyril
A1  - Mitrofanov, Oleg
PB  - Optica Publishing Group
IS  - 6
TI  - Continuous wave terahertz detection using 1550 nm pumped nonlinear photoconductive GaAs metasurfaces
SP  - 9809
UR  - https://doi.org/10.1364/OE.517422
AV  - public
EP  - 9819
JF  - Optics Express
SN  - 1094-4087
N1  - © The Author(s), 2024. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/
ID  - discovery10189665
VL  - 32
N2  - Terahertz (THz) continuous wave (CW) spectroscopy systems can offer extremely high spectral resolution over the THz band by photo-mixing high-performance telecommunications-band (1530-1565 nm) lasers. However, typical THz CW detectors in these systems use narrow band-gap photoconductors, which require elaborate material growth and generate relatively large detector noise. Here we demonstrate that two-step photon absorption in a nano-structured low-temperature grown GaAs (LT-GaAs) metasurface which enables switching of photoconductivity within approximately one picosecond. We show that LT-GaAs can be used as an ultrafast photoconductor in CW THz detectors despite having a bandgap twice as large as the telecommunications laser photon energy. The metasurface design harnesses Mie modes in LT GaAs resonators, whereas metallic electrodes of THz detectors can be designed to support an additional photonic mode, which further increases photoconductivity at a desired wavelength.
ER  -