Modern communication systems rely on efficient quadrature amplitude modulation formats that encode information on both the amplitude and phase of an electromagnetic carrier. Coherent detection of such signals typically requires complex receivers that contain a continuous-wave local oscillator as a phase reference and a mixer circuit for spectral down-conversion. In optical communications, the so-called Kramers–Kronig scheme has been demonstrated to simplify the receiver, reducing the hardware to a single photodiode1,2,3. In this approach, a local-oscillator tone is transmitted along with the signal, and the amplitude and phase of the complex signal envelope are digitally reconstructed from the photocurrent by exploiting their Kramers–Kronig-type relation4,5,6. Here, we transfer the Kramers–Kronig scheme to high-speed wireless communications at terahertz carrier frequencies. To this end, we generalize the approach to account for non-quadratic receiver characteristics and employ a Schottky-barrier diode as a nonlinear receiver element. Using 16-state quadrature amplitude modulation, we transmit a net data rate of 115 Gbit s−1 at a carrier frequency of 0.3 THz over a distance of 110 m.
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The data that support the findings of this study are available from the corresponding author on reasonable request.
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This work was supported by the European Research Council (ERC consolidator grant ‘TeraSHAPE’, no. 773248), the Alfried Krupp von Bohlen und Halbach Foundation, the Helmholtz International Research School of Teratronics (HIRST) and the Karlsruhe School of Optics and Photonics (KSOP). The work relies on instrumentation funded by the European Regional Development Fund (ERDF, grant EFRE/FEIH_776267), the Deutsche Forschungsgemeinschaft (DFG; grants DFG/INST 121384/166-1 and DFG/INST 121384/167-1) and the Hector Stiftung (Hector Foundation).
J.L.H. is chief technology officer of Virginia Diodes Inc., a company manufacturing and selling high-speed SBDs for terahertz signal processing. All other authors have no competing interests.
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Harter, T., Füllner, C., Kemal, J.N. et al. Generalized Kramers–Kronig receiver for coherent terahertz communications. Nat. Photonics 14, 601–606 (2020). https://doi.org/10.1038/s41566-020-0675-0
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