Optically controlled transmission of porous polyethylene terephthalate films filled with nematic liquid crystal

We investigated the influence of blue light (lambda=450 nm) on the optical properties of porous polyethylene terephthalate (PET) films filled with a nematic liquid crystal (E7). In experiments, films of 12 microm thickness with randomly distributed open-end pores of well-defined diameters (170, 400, 850 nm) were studied. It was found that blue-light illumination of the porous PET films preliminarily treated by an azo dye solution resulted in strong intensity changes when the He-Ne laser beam passed through the sample. The observed effect can be attributed to the heating caused by the absorption of blue light by azo dye molecules.