Design of ultra-compact TE mode ring optical isolator using a cobalt ferrite film for silicon photonic integrated circuits

Abstract

In this study, we present the design of an integrated transverse electric mode isolator realized by the epitaxial growth of a cobalt ferrite (CFO) film on a silicon micro-ring resonator structure. Exploiting the large magneto-optical activity of CFO along with the good characteristics of resonator structures, we numerically demonstrated isolator designs with ultra-compact sizes. The use of ring resonator structures with the reduced size is appealing because of lower insertion loss values. The nonreciprocal phase shift was maximized by optimizing the ring cross-section and was further studied in terms of the ring radius employing a transformation optics theory. Finally, we analyzed the optical isolator characteristics in terms of ring size and ring-waveguide power coupling ratio. The computed results pointed out that decreasing the ring size improves the device performance and can ease the device design and fabrication process.