Ultra-broadband Photonic Receiver for (sub-) THz Communication between 100 and 600 GHz enabling Line Rates up to 84 Gbit/s

Photomixers, which convert optical signals into high-frequency electrical signals, are promising sources and detectors for terahertz (THz) wireless communications due to their broad tunability, high bandwidth, and easy integration with fiberoptic networks. Photodiode (PD)-based THz emitters are already the state-of-the-art for highest data rate THz wireless links. Photonic THz receivers, such as photoconductive antennas (PCA), have the same benefits of high THz bandwidth and potentially the same very low phase-noise as PD emitters. However, PCAs have not yet demonstrated competitive receiver performance compared to electronic mixers. This limitation arises from the restricted conversion gain and intermediate frequency (IF) bandwidth of the top-illuminated PCAs used in current systems. In this work, we present a novel photomixing heterodyne THz receiver based on waveguide-integrated (win) PCAs, which offers a 25 dB increase in conversion gain due to benefits arising from the optical waveguide coupling. We design and optimize a high-frequency package for the win-PCAs, achieving a record 3- and 6-dB IF bandwidth of 25 and 40 GHz, respectively. With this receiver, we now attain gross data rates of up to 84 Gbit/s, which is a new record for photonic wireless links with PCA receivers. At the same time, we demonstrate the ultra-broadband operation capabilities of the win-PCA, enabling data transmission at carrier frequencies from 100 to 600 GHz with the same receiver.