Rydberg excitons: a nonlinear optics perspective
For the last decade, highly excited (Rydberg) states of electron-hole bound states (excitons) in the semiconductor Cu2O have been showing more and more similarities with their atomic relatives, enabling solid-state Rydberg physics. After a rapid overview on Cu2O Rydberg excitons, I will focus on two recent experimental results where Rydberg-induced optical nonlinearities are central. In the first case, the giant interactions between Rydberg states are used to produce a large self-Kerr effect. This is directly observed with spatially-resolved interferometric imaging. In a second example, I will discuss very recent result where a second harmonic generation process is time-resolved with sub-picosecond resolution to directly unveil the Rydberg states lifetime along with several other intriguing dynamics.