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Simulations demonstrate that undoped yttrium iron garnet (YIG) seedlayers cause reduced Faraday rotation in silicon-on-insulator waveguides with Ce-doped YIG claddings. Undoped seedlayers are required for the crystallization of the magneto-optical Ce:YIG claddings, but they diminish the interaction of the Ce:YIG with the guided modes. Therefore, new magneto-optical garnets, terbium iron garnet (TIG) and bismuth-doped TIG (Bi:TIG), are introduced that can be integrated directly on Si and quartz substrates without seedlayers. The Faraday rotations of TIG and Bi:TIG films at 1550 nm were measured to be +500°/cm and -500°/cm, respectively. Simulations show that these new garnets have the potential to significantly mitigate the negative impact of the seedlayers under Ce:YIG claddings. The successful growth of TIG and Bi:TIG on low-index fused quartz inspired novel garnet-core waveguide isolator designs, simulated using finite difference time domain methods. These designs use alternating segments of positive and negative Faraday rotation for push-pull quasi phase matching in order to overcome birefringence in waveguides with rectangular cross sections.
Bibliographical noteFunding Information:
This work was supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013 and was supported partially by National Science Foundation via the World Materials Network: DMR-1210818. Parts of this work were carried out in the UMN Characterization Facility. The authors would like to thank the Minnesota Nanofabrication Center (MNC) staff for their valuable support and are grateful for resources from the Minnesota Supercomputing Institute (MSI).
© 2016 American Chemical Society.
- cerium-doped yttrium iron garnet (Ce:YIG)
- Faraday rotation
- optical isolator
- silicon on insulator (SOI) waveguides
- terbium iron garnet (TIG)
- yttrium iron garnet (YIG) seedlayer