Strong Light Matter Coupling in Single Molecule Layers: A Complete Exciton Polarization Theory 

Single layer transition metal disulfides (TMDCs) are a class of two-dimensional materials with significant optical properties. However, there is currently no complete theory to describe polarization modes within a wide range of free electron densities. A team led by Professor Yaroslav Vladimirovich Zhumagulov from the University of Regensburg in Germany has developed a microscopic theory to describe strong light matter coupling in doped transition metal disulfide monolayers over a wide range of free electron densities.

This theory involves a numerical calculation of a set of three body excitations, which are then coupled to the cavity resonant mode in a non perturbative manner. The author used this method to calculate polaron spectra and revealed the rich structure of newly emerged light matter composite quasi particles. The results confirmed that charged excitons exhibit robustness over a wide range of electron concentrations. At the intermediate doping level, the author observed a three mode exciton pole structure, in which the additional mode in the middle of the pole gap qualitatively changed the anti crossing behavior. In addition, the author predicts that in highly doped polarized samples, the oscillator strength of excited charged excitons becomes important and may drive the system into a strongly coupled region with a strange charge distribution.