THz-to-optical conversion in wireless communications using an ultra-broadband plasmonic modulator

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Future wireless communication networks will need to handle data rates of tens or even hundreds of Gbit s−1 per link, requiring carrier frequencies in the unallocated THz spectrum1,2. In this context, seamless integration of THz links into existing fibre-optic infrastructures3 is of great importance to complement the inherent portability and flexibility advantages of wireless networks and the reliable and virtually unlimited capacity of optical transmission systems. On the technological level, this requires novel device and signal processing concepts for direct conversion of data streams between the THz and optical domains. Here, we demonstrate a THz link that is seamlessly integrated into a fibre-optic network using direct THz-to-optical (T/O) conversion at the wireless receiver. We exploit an ultra-broadband silicon-plasmonic modulator having a 3 dB bandwidth in excess of 0.36 THz for T/O conversion of a 50 Gbit s−1 data stream that is transmitted on a 0.2885 THz carrier over a 16-m-long wireless link. Optical-to-THz (O/T) conversion at the wireless transmitter relies on photomixing in a uni-travelling-carrier photodiode.

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Fig. 1: Seamless integration of THz wireless links into fibre-optic infrastructures by direct O/T and T/O conversion.
Fig. 2: Bandwidth measurement of POH modulator.
Fig. 3: Demonstration of THz wireless data transmission using direct O/T and T/O conversion.

Data availability

The data that support the plots within this Letter and other findings of this study are available from the corresponding author(s) upon reasonable request.


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This work was supported by the European Research Council (ERC Consolidator Grant ‘TeraSHAPE’, no. 773248), the DFG project PACE (no. 403188360) within the Priority Programme ‘Electronic–Photonic Integrated Systems for Ultrafast Signal Processing’ (SPP 2111), the BMBF project SPIDER (no. 01DR18014A), the Alfried Krupp von Bohlen und Halbach Foundation, the Helmholtz International Research School of Teratronics (HIRST) and the Karlsruhe Nano Micro Facility (KNMF). We also thank J. Luo and A.K.-Y. Jen from Soluxra for providing the organic EO material.

Author information

S.U., T.H., W.F. and C.K. developed the concept and designed the experiment. S.U. and Z.L. designed the modulators and fabricated them with support from K.K., S.M., S.K.G., A.B. and L.H. S.U. and J.S. characterized the devices. S.U. and T.H. performed the transmission experiments and analysed the data together with J.K. and P.M.-P. Y.K. developed the poling procedure for the POH modulators and formulated the organic EO material. A.T. and M.W. developed and provided the THz MMIC amplifiers. The work was supervised jointly by T.Z., S.R., W.F. and C.K. S.U., W.F. and C.K. wrote the paper. All authors revised the paper.

Correspondence to S. Ummethala or C. Koos.

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Supplementary Information

Supplementary data, analysis and discussion, Supplementary Figs. 1–8 and Supplementary references 1–25.

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Ummethala, S., Harter, T., Koehnle, K. et al. THz-to-optical conversion in wireless communications using an ultra-broadband plasmonic modulator. Nat. Photonics 13, 519–524 (2019) doi:10.1038/s41566-019-0475-6

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