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Updated: Jun 24, 2025

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
Published on: July 8, 2013
Terahertz photon to dc current conversion via magnetic excitations of multiferroics
Makiko Ogino1, Yoshihiro Okamura1, Kosuke Fujiwara1
1Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, Japan.
Abstract:
Direct conversion from terahertz photon to charge current is a key phenomenon for terahertz photonics. Quantum geometrical description of optical processes in crystalline solids predicts existence of field-unbiased dc photocurrent arising from terahertz-light generation of magnetic excitations in multiferroics, potentially leading to fast and energy-efficient terahertz devices. Here, we demonstrate the dc charge current generation from terahertz magnetic excitations in multiferroic perovskite manganites with spin-driven ferroelectricity, while keeping an insulating state with no free carrier. It is also revealed that electromagnon, which ranges sub-terahertz to 2 THz, as well as antiferromagnetic resonance shows the giant conversion efficiency. Polar asymmetry induced by the cycloidal spin order gives rise to this terahertz-photon-induced dc photocurrent, and no external magnetic and electric bias field are required for this conversion process. The observed phenomena are beyond the conventional photovoltaics in semi-classical regime and demonstrate the essential role of quantum geometrical aspect in low-energy optical processes. Our finding establishes a paradigm of terahertz photovoltaic phenomena, paving a way for terahertz photonic devices and energy harvesting.
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