Flexible film waveguides with excellent bending properties

We have developed a film waveguide which has excellent bending properties. The waveguide can be fabricated by existing exposure/development processes and facilities with a core and a cladding dry film. Based on the bending loss simulation results, we fabricated the film waveguides of which the core-cladding index difference (relative index difference) of the waveguide was 3.1% and were evaluated transmission and bending properties. The propagation loss measured by a cut-back method was 0.15dB/cm at wavelength of 850nm. There was little change in optical loss on a 360-degree bend test with a 2mm radius of curvature. No loss increase and no damage to the film waveguide were observed after MIT folding endurance test more than one hundred thousand times with a 2mm bending radius of curvature at -30, 23 and 85 °C. The film waveguide demonstrated good folding endurance over a wide range of temperatures.