Magnetic-field tunable photonic stop band in metallodielectric photonic crystals

We fabricated an artificial crystal consisting of a stack of containers with magnetizable ferromagnetic spheres. In the absence of external magnetic field the particles are in disordered state while in the presence of the field the particles self-assemble in almost a perfect hexagonal order. The degree of order is controlled by magnetic field. We study magnitude and phase of the frequency-dependent mm-wave transmission through the stack as a function of magnetic field. In the ordered state there are well-defined photonic stopbands separated by the regions where transmission is close to unity (transparency windows) while in the disordered state these regions mostly disappear. By varying magnetic field we achieve effective tuning of the mm-wave transmission through the stack. (C) 2003 Elsevier B.V. All rights reserved.