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[6a-A405-4] FDTD analysis of slow light effect in a photonic crystal waveguide for compact on-chip magneto-optical isolator
Keywords:photonic crystal waveguide, optical isolator, magneto-optical effect
For integrated photonics, on-chip optical isolators are inevitably necessary because they suppress the reflection of light and help to maintain the stability of optical components. Though various isolators have been demonstrated, isolators based on magneto-optical effect are particularly promising because of their large isolation ratio and robustness of operation. However, the devise sizes of them are not so small due to the fact that the isolation ratio depends on the interaction length between magneto-optical materials and light. On the other hand, a photonic crystal (PhC) waveguide is effective device to enhance the light-matter interaction because of the achievable slow light effect, so it has potential to shorten the length of magneto-optical isolators. However, we need to use dynamic simulation methods supporting permittivity tensor, which is usually more complicated than the analytic methods, to estimate the influence of the slow light effect correctly because the effect strongly depends on both mode profile and group velocity of the guided mode. In this study, we developed an algorism for finite difference time domain (FDTD) method with permittivity tensor to investigate the impact of the slow light effect on magneto-optical isolator. We found the strong slow light enhance the isolation ratio more than 8 times compared to weak slow light. This result shows the feasibility to realize more compact magneto-optical isolators due to the strong slow light in integrated PhC waveguide platform.