Korringa-Kohn-Rostoker method A-plane 4 Artificial opals 4 Experimental confirmation 4 Front face 4 High-energy range 4 Incident fields 4 Lattice resonances 4 Near field scanning optical microscopy 4 Near-field pattern 4 Near-field scanning optical microscope 4 Optical correlation 4 Optical intensities 4 Optical response 4 Outer surface 4 Periodic structures 4 Rear surfaces 4 Scanning near-field optical microscopy 4 Silicate minerals 4 Three dimensional periodic structure 4 Transmission mode 4 Crystal microstructure 2 Electromagnetic methods 2 Electromagnetic response 2 Energy gap 2 Geometry 2 Natural photonic crystals 2 Photonic band gap 2 Photonic crystals 2 Photonic structure 2