Photoinduced Phase Change in SnSe Probed by Ultrafast Multi-THz Spectroscopy

We use time-resolved multi-terahertz spectroscopy to measure the transient reflectivity and extract the optical conductivity of SnSe after femtosecond optical excitation. Polaron-like photoconductivity features are observed. The change in conductivity spectra and dynamics are strongly dependent on excitation density. Thresholded behavior depending on pump fluence supports a non-thermal change of state after ultrafast excitation of the electronic subsystem.