Tuning light transmission with smart fluids based on 1D carbon nanomaterials

This work reports on a study of light transmission in electrically responsive materials consisting of long aspect ratio carbon nanostructures in fluid matrices. Composite fluids were prepared using multiwalled carbon nanotubes or carbon nanofibers in two types of fluid matrices, ethylene glycol and distilled water. Measurements were performed illuminating the sample with polarized light. Before, during and after applying a uniform and constant electric field, the evolution of the intensity of the transmitted light was monitored. For ethylene glycol-based dispersions, it was found that the applied electric field induces substantial changes in the polarization component of the incident light parallel with the electric field vector. In contrast, for the same dispersions, the optical transmission of the light polarized in the direction perpendicular to the electric field does not show appreciable changes. The matrix fluid properties were found to be crucial for the electro-optical effect: in distilled water-based dispersions, no changes of transmission were found upon applying an electric field for any of the polarization components of the light. It was also shown that the polarization of the transmitted light can be dynamically adjusted in time and space by varying the applied voltage across ethylene glycol dispersions. The electric control of the light polarization opens the possibility of using these simple systems as light dimmers or in a more sophisticated application such as reversible dynamic polarizers.