Wireless data traffic increases by a factor of 100 every 10 years and, in 10 years’ time, we will have to provide data rates of even Tb/s. Given Shannon’s limit, a more efficient use of available spectrum will not suffice to reach the predicted data rates. The use of carrier frequencies in the sub-Terahertz (sub-THz) regime (between 100 GHz and 1 THz) will be pivotal to achieve the total bandwidths (BWs) required for front- and back-hauling in beyond 5G systems, ultra-high definition multimedia streaming and data centers. Moreover, sub-THz frequencies have not yet been allocated and they pre-sent atmospheric transmission windows with attenuation below 10 dB/km. To enable the use of this frequency band, we will need adequate front-ends with high gain and beam steering capabilities to receive/transmit efficiently in point-to-point and point-to-multipoint scenarios. The first challenge in sub-THz wireless communications consists in designing high-gain antennas efficiently coupled to continuous-wave THz sources at room temperature, to compensate for the propagation losses. The second hurdle lies in the lack of sources with adequate output power in the sub-THz range. Finally, one must to provide beam steering capabilities to guarantee an excellent alignment of the narrow beams.


The overall objective of this thesis will be to develop sub-THz front-ends by photonic generation with several disruptive proofs of concepts at international level:

– One of the first high-gain photomixing antenna array with broad bandwidth. We will investigate the integration of UTC-photodiodes with planar wideband antennas. Special attention will be paid to find the most appropriate materials and fabrication techniques for these arrays.

– The developed photomixing arrays will also provide beam steering capabilities. By bringing one fiber to each photodetector, it is possible to control the phase of each element with true time delay and provide either beam steering or multiple beams.

– Implement currently developed dual frequency optical sources to achieve the sub-THz carrier compatible with photo-mixer arrays.

– Last but not least, the realized prototypes will be measured at IETR/Institut Foton facilities, and real-time high data rates over medium or long distances in point-to-multipoint scenarios.

Date limite:

May 16, 2022


  • Prof. Mehdi ALOUINI, Université de Rennes 1

Institut Foton, UMR CNRS 6082, Rennes

  • Dr. David GONZÁLEZ OVEJERO, Chargé de recherche, CNRS

IETR, UMR CNRS 6164, Rennes

  • Prof. Ronan SAULEAU, Université de Rennes 1

IETR, UMR CNRS 6164, Rennes

  • Prof. Cyril PARANTHOEN, INSA Rennes

Institut Foton, UMR CNRS 6082, Rennes