Ultrafast nonlinear dynamics in thin GaN films studied by femtosecond digital holographyN. Šiaulys, A. Urniežius, T. Stanislauskas, T. Malinauskas, V. Kudriašov and A. MelninkaitisEPJ Web of Conferences, 41 (2013) 04007DOI: https://doi.org/10.1051/epjconf/20134104007