INVESTIGATION OF ABSOLUTE PHOTONIC BAND-GAPS IN 2-DIMENSIONAL DIELECTRIC STRUCTURES

We examine the photonic band structure of two-dimensional (2D) arrays of dielectric holes using the coherent microwave transient spectroscop y (COMITS) technique. Such 2D hole arrays are constructed by embedding low-index rods (air) in a dielectric background of higher-index Styca st material (n=3.60). The dispersion relation for electromagnetic wave propagation in these photonic crystals is directly determined using t he phase sensitivity of COMITS. We find that both the square and trian gular lattice structures exhibit photonic band gaps that are common to both polarizations for all wave-vectors along major symmetry axes. In addition, the connectivity of the high-index dielectric and the openi ng of a large gap for propagation with E field perpendicular to the ho le cylinders are found to be important criteria for generating a large absolute photonic band gap.