Magnetocontrollable photonic crystals based on colloidal ferrofluids

We theoretically exploit a class of one-dimensional double-layer photonic crystals based on colloidal ferrofluids, which are made of ferromagnetic nanoparticles suspended in a carrier liquid. Depending on the magnetic-field-induced anisotropic property of the ferrofluid, precise controllability of the band gaps is demonstrated to be possible by applying an appropriate external magnetic field. (C) 2008 American Institute of Physics.