Optically induced elasto (piezo-)-optics effect (EOE) in the benzene large-sized nanocrystallites with sizes 80-100 nm incorporated within the polyvinyl alcohol matrices was observed for the first time. A correlation between the number of macrovacancies measured by positron annihilation and the values of EOE coefficient indicates on appearance of enhanced static dipole moments caused by defects. Simultaneously changes of time kinetics of the EOE in picosecond time regime is observed. A substantial role of electron-phonon subsystem in the observed EOE is shown. (C) 2004 Elsevier B.V. All rights reserved.