Nonlinear terahertz responses of optically excited Cu2O

Dr. Changqing Zhu, Ms. Anneke Reinold, Mr. Patrick Pilch, Prof. Marc Assmann, Prof. Zhe Wang
TU Dortmund University, Dortmund, Germany


Excitons in Cu2O have attracted significant attention due to their peculiar properties, such as the remarkable Rydberg series with the principal quantum number extending up to 30[1, 2] and the realization of Bose-Einstein condensation[3]. We report on time-resolved nonlinear terahertz spectroscopic study of optically excited nonequilibrium states in Cu2O. Terahertz harmonic generation is observed and investigated as a function of the fluence of the optical excitation and by varying the delay between the optical excitation and the terahertz driving pulse. Our time-resolved spectroscopic techniques allow us to associate the observed nonlinear terahertz responses with different processes of exciton-related dynamics.