J. Mangeney – 12 novembre

Terahertz (THz) radiation is extremely appealing for fundamental research as well as for a large number of applications, such as security screening and astrophysics science. However, the THz spectral range remains one of the least technologically developed spectral regions owing to the lack of compact powerful sources. Graphene and related nanostructures are very promising materials for coherent THz emission and lasing. Indeed, THz photons can induce interband transitions in graphene and related nanostructures, the optical phonon energy is very high (200 meV) and the linear electronic dispersion in graphene provides enhanced nonlinear effects.
In this talk, I will introduce large graphene quantum dots (d~100 nm), their electronic state distribution close to the Dirac point predicted by our calculation and our recent technological developments for their fabrication. I will present our results on transport and optical spectroscopy of a graphene quantum dot based device and show its capability to act as an ultrasensitive THz spectrometer. At last, I will briefly present long carrier lifetimes in graphene/hBN heterostructures opening interesting perspectives to exploit this material system for coherent THz emission.