In communications, the frequency range 0.1-30 THz is essentially terra incognita. Recently, research has focused on this terahertz gap, because the high carrier frequencies promise unprecedented channel capacities. Indeed, data rates of 100 Gbit s(-1) were predicted for 2015. Here, we present, for the first time, a single-input and single-output wireless communication system at 237.5 GHz for transmitting data over 20 m at a data rate of 100 Gbit s(-1). This breakthrough results from combining terahertz photonics and electronics, whereby a narrow-band terahertz carrier is photonically generated by mixing comb lines of a mode-locked laser in a uni-travellingcarrier photodiode. The uni-travelling-carrier photodiode output is then radiated over a beam-focusing antenna. The signal is received by a millimetre-wave monolithic integrated circuit comprising novel terahertz mixers and amplifiers. We believe that this approach provides a path to scale wireless communications to Tbit s(-1) rates over distances of >1 km

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Photonics might play a key role in future wireless communication systems that operate at THz carrier frequencies. A prime example is the generation of THz data streams by mixing optical signals in high-speed photodetectors. Over the previous years, this concept has enabled a series of wireless transmission experiments at record-high data rates. Reception of THz signals in these experiments, however, still relied on electronic circuits. In this paper, we show that wireless THz receivers can also greatly benefit from optoelectronic signal processing techniques, in particular when carrier frequencies beyond 0.1 THz and wideband tunability over more than an octave is required. Our approach relies on a high-speed photoconductor and a photonic local oscillator for optoelectronic down-conversion of THz data signals to an intermediate frequency band that is easily accessible by conventional microelectronics. By tuning the frequency of the photonic local oscillator, we can cover a wide range of carrier frequencies between 0.03 THz and 0.34 THz. We demonstrate line rates of up to 10 Gbit/s on a single channel and up to 30 Gbit/s on multiple channels over a distance of 58 m. To the best of our knowledge, our experiments represent the first demonstration of a THz transmission link that exploits optoelectronic signal processing techniques both at the transmitter and the receiver. LO LO,a LO,b ff f of two unmodulated c.w. tones acts as photonic local oscillator (T-wave-to-electric conversion, T/E).

We demonstrate a 16-pixel array of radio-frequency superconducting nanowire single-photon detectors with an integrated and scalable frequency-division multiplexing architecture, reducing the required bias and readout lines to a single microwave feed line. The electrical behavior of the photon-sensitive nanowires, embedded in a resonant circuit, as well as the optical performance and timing jitter of the single detectors is discussed. Besides the single pixel measurements we also demonstrate the operation of a 16-pixel array with a temporal, spatial and photon-number resolution.