Processing techniques for polymer optical waveguides

In this paper a comparison of processing techniques for polymer waveguides will be presented. This includes a detailed description of the processing techniques, a discussion of the choice of polymer constituents (resin, photoinitiator, and diluent), and a discussion of the mechanical and optical properties of waveguides fabricated using both techniques. By comparing processing techniques, insight about how various processing parameters affect guide properties such as the optical attenuation can be gained. This information can be used to refine the processing techniques and thereby reduce the losses in these materials to a minimum and to refine the chemistry of the polymers to improve upon their optical and mechanical properties. We have addressed how various processing parameters affect the waveguide properties by studying two different processing techniques. Using a laser-writing technique, we fabricated waveguides with record-low losses of 0.08 dB/cm at a wavelength of 633nm. Previous results indicate that the losses will be even lower at a wavelength of 800 nm. The experiments indicate that there is a tradeoff between exposure time and processing power that determines the best waveguide mechanical properties. Also, waveguides processed with the lowest total energy result in the most desirable optical properties. Low energy processing can be accomplished by either reducing the exposure time and/or reducing the incident power. Our study indicates that two properties of the polymers must be modified in future work: 1. improving the adherence of the polymers to the substrates in this region, and 2. reducing the power density that is required to cure the full layer thickness. These properties must be attained without compromising the optical attenuation of the waveguides.