Transition Metal Dichalcogenides (TMDCs) show fascinating nonlinear optical properties in the presence of strong terahertz and mid-infrared fields.
TMDCs are a class of layered materials consisting of transition metals (M: Mo, W) and chalcogen atoms (X: S, Se, Te) which form a compound, MX2. If the bulk material is exfoliated to monolayers the former indirect semiconductor is transformed into a direct semiconductor. Additionally, in this monolayer the electronic screening is reduced, leading to exciton binding energies of several hundred meV. Terahertz radiation is utilized to investigate the different excited states of these excitons.
This research interest is part of the TRR 142 - Tailored Nonlinear Photonics.