Tunable photonic crystals based on MnFe2O4 magnetic fluids by magnetic fields

The model of photonic crystals (PCs) formed in magnetic fluids under externally magnetic fields is established and the mechanisms of tunability are expounded. The magnetic-field-dependent structure ratio and refractive index contrast of the photonic crystals are derived from the experimental data about the structures and refractive indices for a MnFe2O4 magnetic fluid under externally magnetic fields. Band diagram calculations display the tunability of the forbidden bands with magnetic field strength for both TE and TM modes. Furthermore, the number of the forbidden bands for the TE mode increases with the magnetic field strength. (C) 2009 Elsevier B.V. All rights reserved.