Direct laser fabrication of diffraction gratings on polymer thin films and waveguides

With the increasing interest in polymer integrated optical devices, techniques for fabrication of efficient polymer diffraction gratings are of critical importance to aid in coupling of light into and out of polymer waveguides. We have been developing direct laser fabrication techniques for diffraction gratings and standard photo-lithographic techniques for polymer waveguides. The investigation of the laser fabrication is carried out using a 193 nm ArF excimer laser. Symmetric and blazed gratings were fabricated on polymer thin films and characterized. Diffraction efficiencies into a single order as high as 79% have been observed. In addition, gratings were fabricated on multi-mode polymer dispensed waveguides for use as input couplers and on single mode photo-lithographically fabricated polymer waveguides for use as output couplers. Output coupling efficiencies of 32% have been observed.