PHOTONIC BAND-STRUCTURE OF 3D ORDERED SILICA MATRICES

The symmetry and orientation of a photonic lattice of 3D ordered porou s silica matrices (synthetic opals) are determined by analysis of tran smission electron micrographs. By optical transmission measurements th e photonic band edges are mapped out at points L and K of the Brilloui n zone. It is shown that modulating the refractive index of opal pores by filling them with liquids results in variation of the light attenu ation length within the forbidden gap. To increase the refractive inde x contrast of the lattice, the pores of opals were filled with CdS. A dramatic decrease in attenuation length is observed for opal/CdS. The parameters of a photonic lattice with a 'pseudo-gap', that is, with a prominent depletion of the photonic density of states, are estimated. (C) 1997 Academic Press Limited.