Europium-substituted cerium iron garnet thin films for silicon-integrated nonreciprocal photonic device applications

Optical nonreciprocal devices are key components in photonic integrated circuits. Cerium-doped yttrium iron garnet (Ce:YIG) has been widely studied for nonreciprocal photonic devices in the telecommunication wavelength range. Despite recent progress, challenges arise when depositing polycrystalline Ce:YIG thin films on non-garnet substrates, resulting in weaker magneto-optical performance due to Ce4+ segregation. In this paper, we report enhanced Faraday rotation (FR) and figure of merit (FoM) in Ce:EuIG films deposited on silicon. We demonstrate a high Ce3+ concentration of 81.36%, FR of −3225 deg/cm, and elevated FoM of 33.1 deg/dB in silicon-integrated polycrystalline Ce:EuIG thin films by utilizing a two-step growth process involving magnetron sputtering and rapid thermal annealing. These results highlight the promising potential of Ce:EuIG for nonreciprocal photonic devices.