(95d) Photolithography and Nanoparticle Synthesis for Optical Waveguides

Optical waveguides offer a compact way to correct the problem of polarization plane rotation, which can result in data corruption, in light signals traveling long distances through fiber optic cables. Waveguides use the Faraday effect of magnetic particles embedded in a polymer matrix to counter-rotate light signals, restoring the polarization planes to their original state. The magnetic fields required for this rotation would be prohibitively strong, however, without the inclusion of bismuth yttrium iron garnet (Bi-YIG) nanoparticles to the waveguide polymer matrix. Preliminary SEM results suggest that these nanoparticles can be synthesized through a urea co-precipitation reaction. Additionally, the magnetic field strengths of composite magnets based on three different polymers were studied, and photolithography procedures (i. e. spin speed, UV exposure time) needed to produce the correct thickness for each of the multiple layers of the waveguide and clear waveguide features were developed. Composite magnets based on the commercial photoresist SU-8 could be magnetized to at least 20 gauss in a little less than four hours, whereas magnets based on polymethyl-methacrylate (PMMA) did not ever achieve field strength of more than 10 gauss.