A more efficient use of the available spectrum does not suffice to reach the bandwidths (BWs) of several tens of GHz required by future wireless systems. Thus, the use of the 275-350 GHz frequency range is the key to enable ultra-large BW wireless, owing to the following advantages: a) it has not yet been allocated; b) it presents atmospheric attenuation windows, which enable mid-range links and small cell deployment; c) the short wavelengths favor integration and packaging; and d) THz links are less susceptible than optical wireless to air turbulence and humidity, fog, smoke, and rain.
The main challenge in THz wireless communications consists in designing low-profile high-gain antennas efficiently coupled to continuous-wave THz sources at room temperature, to compensate for the propagation loss. Moreover, appropriate radiation patterns must be tailored for the antennas according to the needs of each THz wireless system.
The carrier in the transmitter will be generated using optical heterodyning by mixing two optical wavelengths on a photodiode, which presents an output electrical signal in the THz range, equal to the wavelength spacing of the two optical tones. This photonic approach is particularly convenient for communications due to its wide bandwidth, tunability and stability. It also allows one to stablish a direct bridge between 1.55μm data flows in optical fibers and THz radio.
First, we will investigate the efficient radiation of the photocurrent generated in the photodetector, overcoming the impedance mismatch between antenna and photomixer. Second, appropriate radiation patterns must be tailored for the antennas in each THz wireless system. Hence, we will pursue photoconductive antenna arrays with agile radiation patterns.
The candidate must have worked at least 12 months outside France during the last 3 years, as required by Britany Region.
All information about candidate profile and required skills can be found in this document.