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arXiv · 2501.06091

Room-temperature, continuous-wave Terahertz generation in free-space with an intersubband mid-infrared photomixer

Q. Lin·J-F. Lampin·G. Ducournau·S. Lepillet·H. Li·E. Peytavit·S. Barbieri
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Abstract

We demonstrate a Terahertz photomixer pumped by mid-infrared photons at 10$\mu$m wavelength. The device is based on a dual-antenna architecture, in which a two-dimensional array of mid-infrared patch-antenna resonators is connected to the electrodes of a log-spiral Terahertz antenna. By exploiting intersubband absorption inside an AlGaAs-GaAs multi-quantum-well heterostructure, a photocurrent is coherently generated at the difference frequency between two quantum cascade lasers. The photocurrent drives the antenna electrodes allowing tunable, continuous-wave generation in free-space up to 1 Terahertz at room temperature. By experimentally studying the photomixer frequency response and dark impedance, we demonstrate that the observed power roll-off at high-frequency is limited by the combined effect of the photoexcited carrier's intrinsic lifetime and of the device $RC$ time constant. In the spectral range investigated we obtain, in continuous-wave, mid-infrared $\rightarrow$ Terahertz conversion efficiencies exceeding by orders of magnitude those of unipolar devices exploiting $\chi^{(2)}$ processes.

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Q. Lin, J-F. Lampin, G. Ducournau, S. Lepillet, H. Li, E. Peytavit, S. Barbieri. 2025-01-10. Room-temperature, continuous-wave Terahertz generation in free-space with an intersubband mid-infrared photomixer. https://arxiv.org/abs/2501.06091

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