2-DIMENSIONAL TUNABLE PHOTONIC CRYSTALS

We call a photonic crystal tunable if its spectrum can be altered by a n external electric or magnetic held. One of the two constitutive comp onents of the proposed periodic composite structure has either electri c permittivity or magnetic permeability dependent on the external elec tric or magnetic field. Consequently, the electromagnetic spectrum of the photonic crystal can be altered over a wide range by the external quasistationary uniform field. The tunable photonic crystal exhibits s ome useful features reminiscent of those accompanying the well-known e lectronic topological phase transitions in metals. Thorough theoretica l analysis of a two-dimensional tetragonal periodical structure is und ertaken. This specific periodic structure exhibits the most important features of a tunable photonic crystal.