Gupta, A., Jutas, R., Gollner, C., Baltuška, A., Pugžlys, A., & András Fülöp, J. (2026). Broadband GaP contact-grating terahertz source pumped at 3.9 µm. Optics Express, 34(8), 13663–13674. https://doi.org/10.1364/OE.588300
A gallium phosphide (GaP) semiconductor contact-grating THz source with trapezoidal grating groove profile, pumped at a mid-infrared wavelength of 3.9 µm, was demonstrated. The source can be scaled to high electric fields beyond 1 MV/cm due to the plane-parallel geometry, the availability of large GaP single crystals of good quality, and the large bandwidth extending from 0.2 THz to 6 THz. Due to the long pump wavelength, the lowest-order effective multiphoton absorption was 9-photon absorption, which enabled exceptionally high usable pump intensities up to 310 GW/cm². Saturation of THz generation efficiency occurred at a high pump intensity of about 160 GW/cm², caused by pump-induced free-carrier generation which can be explained by multiphoton and Keldysh tunnel ionization models.
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Project title:
Intensive, verstimmbare, schmalbandige THz Quellen: I 5590-N (FWF - Österr. Wissenschaftsfonds) Holmium Amplifier for Breakthrough Research and Industrial Applications: 867822 (European Commission)
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Project (external):
National Research, Development and Innovation Office
CC BY 4.0
