Enhancement of Faraday effect in one-dimensional magneto-optical photonic crystal including a magnetic layer with wavelength dependent off-diagonal elements of dielectric constant tensor

Optical and magneto-optical properties of one-dimensional magneto-optical photonic crystal (1-D MPC) prepared by the sol–gel dip-coating method, including a magnetic defect layer composed of mixture of CoFe2O4 and SiO2, are investigated from both the experimental and theoretical standpoints. The resonant transmission of light was observed around 570nm in the photonic band gap. The Faraday rotation angle θF showed two maxima at 490 and 640nm, and the wavelength dependence of θF above 760nm was similar to that of the CoFe2O4+SiO2 single-layer film. The two maxima of θF are attributed to the enhanced Faraday rotation of nonmagnetic TiO2 layers in the cavity structure and that in magnetic CoFe2O4+SiO2 layer through the light localization in MPC. The maximum value of θF due to the magnetic CoFe2O4+SiO2 layer in the MPC was 22-times larger than that in the single-layer film. The simulation study of MPC with CoFe2O4+SiO2 magnetic defect layer, based on the matrix approach method, showed that the resonant light transmission was accompanied by the localization of electric field, and large enhancement of θF appeared at different wavelengths so as to agree with the experimental features. This can be explained in terms of the wavelength dependent off-diagonal components of the dielectric constant tensor in addition to the large extinction coefficient in the CoFe2O4+SiO2 magnetic defect layer. ► 1-D magnetic photonic crystal (MPC) prepared by sol–gel method. ► Enhancement of Faraday rotation due to the magnetic defect layer of CoFe2O4. ► Shift of wavelength of Faraday rotation maximum from resonant light transmission.