Prof. Dr. Giancarlo Soavi
Abbe Center of Photonics, FSU Jena
spricht zum Thema:
Engineering nonlinear optics in atomically thin materials: ultrafast light modulators and nonlinear valleytronics
"Atomically thin materials and related layered structures are ideal candidates for ultrafast and nanoscale nonlinear devices, such as light modulators and frequency converters. In this seminar, I will discuss some of our recent works in two emerging fields that belong the realm of nonlinear optics.
First, I will discuss the tuning and engineering of nonlinearities in graphene and TMDs by electrical and all-optical means. In graphene, ultra-broadband modulation of third harmonic generation can be obtained via an external gate voltage by tuning the Fermi Energy across multi-photon resonances occurring within the Dirac cone, while all-optical modulation can be ascribed to the combined effect of increased electronic temperature and Pauli blocking.
In the second part of the talk, I will discuss the emerging field of nonlinear valleytronics. In monolayer TMDs, the K/K’ valleys can be selectively excited with circularly polarized light of opposite helicity, but the detection of a valley imbalance, either due to a real excited state population or simply induced by lifting the energy degeneracy between the valleys, has been limited to date to the realm of linear optics. I will show our new approach to valleytronics that allows to detect a valley polarization based on the ultrafast and non-invasive nonlinear process of second harmonic generation, in combination with a generation mechanism based on the ultrafast and coherent optical Stark effect."
Interessenten sind herzlich eingeladen.
Prof. Dr. Korn