The authors present a detailed study of the nonresonant 3rd-order ultrafast response of TiO2 nanostructured films, combining a classical heterodyned optical Kerr effect expt., with 2 polarization selective Kerr techniques, based on transient lensing and phase modulation effects. The complementarity of these techniques is highlighted and demonstrated with calcns. Different aspects of the exptl. results are addressed in detail and, finally, the possibilities of performing expts. on liq. dynamics in the pores of TiO2 films, are discussed in the light of the present results. (c) 2008 American Institute of Physics.