Photonic bandgap optimization in inverted fcc photonic crystals

We present results of photonic band-structure calculations for inverted pho tonic crystal structures. We consider a structure of air spheres in a diele ctric background, arranged in an fee lattice, with a cylindrical tunnel con necting each pair of neighboring spheres. We derive (semi)analytical expres sions for the Fourier coefficients of the dielectric susceptibility, which are used as input in a standard plane-wave expansion method. We optimize th e width of the photonic bandgap by applying a gradient search method and va rying two geometrical parameters in the system: radius, and R-c, is the cyl inder radius. It follows of photonic-crystal structure with air spheres and cylinders in silicon is Delta w/w(0) the ratios R/a and R-c/R, where a is the lattice constant, R is the sphere from our calculations that the maxima l gap width in this type (0) = 9.59%. (C) 2000 Optical So- ciety of America [S0740-3224(00)00404-5] OCIS codes: 260.2030, 160.4760, 000.4430, 160.4670 , 260.2110.