EXISTENCE OF A PHOTONIC BAND GAP AND UNDERLYING PHYSICAL PROCESSES

Mechanisms of the overlapping of gaps due to a refractive index difference minimum and Anderson localization for photonic band gap (PBG) have been used and they give a refractive index contrast difference of less than two percent for X-, L-, and W-points of the Brillouin zone for the pseudogap. Another physical process for the existence of PBG is the use of scattering strength (ε r ≥ 1) for fcc lattice structure. We have found refractive index contrast in the range 2.41–14.21 for the existence of the complete photonic band gap for bound photons (ε r ≥ 1). The lowest limit to yield a gap is 2.41 for valence photons (ε r = 1) at volume filling fraction 85.5% for spherical air atoms and at 14.5% for dielectric spheres. This work is reported for the first time and it is useful for maintaining connectivity and for easier fabrication of photonic crystals.