Faraday effect enhancement in Co–ferrite layer incorporated into one-dimensional photonic crystal working as a Fabry–Pérot resonator

We fabricated a one-dimensional magnetophotonic crystal (MPC), in which a magnetic layer of Co–ferrite (∼40 nm in thickness) is sandwiched by a couple of dielectric multilayer reflectors with (SiO2/TiO2)×7 structure. The Co–ferrite layer was synthesized by ferrite plating from aqueous solution at 90 °C. The MPC is so designed to enhance magneto-optical Faraday rotation θF at the Fabry–Pérot resonance wavelength λ of the multilayer structure. θF was observed to increase by factor of ∼5.4, but at λ=∼620 nm which is deviated from the target resonance (λ=740 nm) and at very weak transmissivity. This may be because the Co–ferrite layer is rough in surface and smaller in thickness than the target thickness at which Fabry–Pérot resonance is designed to occur.