Compact THz lasers based on graphene quantum dots – LEON

The ambition of this project is to open new horizons in the field of graphene-based devices for THz technology. The objective is to develop compact THz amplifiers and lasers operating at room temperature comparable to the concept of semiconductor lasers in the visible range. This long term goal cannot be achieved with the current state-of-the-art scientific and technological approaches.
THz radiation is extremely attractive for fundamental investigations of matter and a critical mass of applications appearing in security screening, medical imaging, astrophysics and atmospheric science to name a few. However, the THz spectral range remains one of the least exploited spectral regions, mainly due to the lack of compact powerful sources. At important bottleneck in the development of the typical semiconductor-laser scheme emitting at THz frequencies has been hampered owing to the absence of an appropriate material with a sufficiently small bandgap.
This project addresses this technological blocking point with new semiconductor-laser schemes for THz emission centred on the integration of graphene-based materials.
Graphene is potentially an excellent candidate for a THz semiconductor-laser model owing to its ‘zero’ bandgap. However, non-radiative recombination mechanisms, especially Auger recombination, reduce the lifetime of the optical gain to few hundreds of femtoseconds. This phenomenon limits the realisation of a THz laser. In order to suppress these detrimental processes, a new concept is needed. The project proposes to exploit the full discretization of electronic states in graphene quantum dots.
The project has three main cornerstones: i) the demonstration of THz amplifiers based on graphene quantum dots, ii) the demonstration of THz lasers based on graphene quantum dots in a microcavity, iii) the exploitation of these THz amplifiers/lasers for homeland security and telecommunication applications.