Porous Polyethylene Terephthalate Optical Waveguide for Sensing Applications

We report the fabrication and characterization of optical waveguides using porous polyethylene terephthalate (PET) film. An optical waveguide is produced by exposing the PET film to cyclotron followed by selective chemical etching. Considering that the average refractive index of porous regions is lower than that of non-porous regions, a waveguide can be formed using a single optical material system. A single-material channel waveguide and an optical splitter were demonstrated using our proposed technique. Through placing a liquid crystal inside the pores, an ethanol gas sensor was obtained with a single-material channel waveguide structure. These PET film waveguides can create new opportunities in various optical applications, particularly in chemical sensing applications.