The objective of this study is to theoretically devise an on-chip optical isolator which is monolithically integrated with a semiconductor waveguide layer yielding low loss. The optical properties of iron are modeled for the use of optical waveguide isolators by improving the Brendel-Bormann model. Our model for iron shows excellent fit with the optical data up to 30 electronvolts (eV). The semiconductor optical waveguide isolator with magneto-optic layers based on non-reciprocal loss shift is developed in this study. Fe, Co, and Ni metals as well as cerium-substituted yttrium iron garnet (Ce:YIG) have been used as magneto-optic layers. We have shown that the isolation ratios of the devices with Fe, Co, Ni metals yield promising results. However, the insertion loss values are in very high ranges due to their large optical absorptions that prevents these metals from being the best candidates for the use of optical isolators. Since magnetic garnets are better candidates for optical waveguide isolators -thanks to their low loss and large Faraday rotation properties- we utilize Ce:YIG as a magneto-optic material for the proposed isolator design. The study is unique in using magnetic garnets as a magneto-optic material for semiconductor waveguide optical isolators. A high amount of isolation ratio of 55 dB is attained while the insertion loss is fairly low at the level of 0.47 dB/mm. The limitation of this study with Ce:YIG is mainly attributed to its large footprint. Apart from that, Ce:YIG material is demonstrated to be a favorable candidate for on-chip isolator applications.
Optical isolators; monolithic integration; semiconductor waveguide; magnetic garnets; magneto-optic materials; ferromagnetic metals; Brendel-Bormann Model; integrated magneto-optical isolator.
Jerome K. Butler
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Oztekin, Reyhane, "A Comparative Analysis of Integrated Optical Waveguide Isolators with Magneto-Optic Layers" (2018). Electrical Engineering Theses and Dissertations. 5.