Light intensity-induced phase transitions in graphene oxide doped polyvinylidene fluoride

The coupling of light with low-frequency functionalities of dielectrics and liquid crystals and an ability to turn "on" and "off" the pyro-, piezo-, or ferro-electric properties of materials on demand by optical means leads to fascinating science and device applications. Moreover, to achieve all-optical control in nano-circuits, the coupling of the light with mechanical degrees of freedom is highly desirable and has been elusive until recently. In this work, we report on the light intensity-induced structural phase transitions in graphene oxide doped piezoelectric polyvinylidene fluoride (PVDF) film observed by micro-Raman spectroscopy. Increasing the laser power results in a steady transformation of the Raman spectrum featured piezoelectric beta phase to one of non-piezoelectric alpha structure. This effect is accompanied by volumetric change of a PVDF unit cell by a factor of two, useful for a photostriction materials application. Furthermore, we observed the reversible switching of alpha and beta phases as a function of the light intensity (laser power between 5.7-31.3 mW). This opens up a new route for multi-functionality control where strain, piezoelectric constants and polarization can be modified by light. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.