Integration of Garnets and Magnets for Waveguide Isolators

This proposal will enable the most efficient integration of NASA?s semiconductor lasers into strategic optical systems. To protect laser lifetimes and increase performance, these lasers will require isolators to protect them from back-reflections, similar to the isolators in all fiber-optic networks. This work proposes to monolithically integrate magneto-optical isolators with semiconductor platforms in order to reduce the size and weight, as well as increase the performance, of NASA?s semiconductor laser systems. The important elements in an integrated isolator are 1) magneto-optical waveguides and 2) permanent magnet biasing films. Yttrium iron garnet (YIG), the strongest magneto-optical material, is very difficult to grow onto semiconductor platforms. This work will use a novel technique, metallorganic chemical liquid deposition (MOCLD) to achieve this feat. Preliminary results have demonstrated the feasibility, but not the optimization, of this technique. Permanent magnet films of SmCo have also demonstrated promise as biasing magnets in waveguide isolators. Here, SmCo films will be made using a novel in-situ nitriding technique during Sm and Co codeposition. Also proposed is the optimization of buffer layers, which buffer substrates during growth and act as optical claddings. Ridge and interferometer components will be modeled using the beam propagation method before prototype isolators are fabricated.