Figure 20.1. Schematic illustrations of 1D, 2D, and 3D photonic crystals patterned from two different types of dielectric materials.

Figure 20.2. Photonic band structures (normal incidence) calculated for a typical 1D photonic crystal made of alternating thin layers of two dielectric materials. The periodicity of the lattice is a, and the dielectric constants are (A) 1=13, 2=13;

and (B) 1=13, 2=12. The hatched region

represents a photonic band gap. Any electromagnetic wave whose frequency falls anywhere in this gap will not be able to propagate through this crystal.

Figure 20.3. (A) An illustration of the 3D woodpile lattice and (B) its photonic band structure calculated using the PWEM method. The filling fraction of the dielectric rods is 26.6%, and the contrast in refractive index is set to be 3.6/1.0.(From Ref. 23 by permission of Elsevier B.V.)

Figure 20.4. A schematic illustration showing the microfabrication of a 3D woodpile lattice of polycrystalline silicon in a layer-by-layer fashion.

Figure 20.5. (A) A schematic illustration of the experimental setup for holographic patterning that involves the use of four coherent laser beams. (From Ref. 36 by permission of Nature Publishing Group.) (B) The scanning electron microscopy image of a 3D periodic lattice generated in a photoresist through photo-induced polymerization. (From Ref. 37 by permission of American Chemical Society.)

Figure 20.6. A schematic illustration of the microfluidic cell used to fabricate opaline lattices from monodispersed spherical colloids (polystyrene beads or silica spheres).

Figure 20.7. Scanning electron microscopy images of two typical examples of 3D opaline lattices that were crystallized from polystyrene beads, with their (111) and (100) crystallographic planes oriented parallel to the surfaces of the supporting substrates, respectively. (From Ref. 63 by permission of WILEY-VCH Verlag GmbH & Co. and from Ref. 66 by permission of American Chemical Society.)

Figure 20.8. (A) The photonic band structure calculated for a 3D opaline lattice consisting of spherical colloids with a refractive index of 3.0. This system only exhibits a stop band between the 2nd and 3rd bands. (From Ref. 70 by permission of WILEY-VCH Verlag GmbH & Co.) (B) The transmission and reflectance spectra recorded from an opaline lattice made of polystyrene beads. The fine features on the spectra were caused by interference of light bounced back from the front and back surfaces of the sample.

Figure 20.9. A schematic illustration of the experimental procedure that generates 3D inverse opals by templating against an opaline lattice of spherical colloids, followed by selective removal of the colloidal templates. (From Ref. 46 by permission of WILEY-VCH Verlag GmbH & Co.)

Figure 20.10. Scanning electron microscopic images of two typical examples of inverse opals that were fabricated by templating the UV-curable liquid organic prepolymer to poly(acrylate methacrylate) against an opaline lattices of polystyrene beads. The polystyrene beads had been selectively removed by etching with toluene. The (111) and (100) plane of these two samples were oriented parallel to the supporting substrate, respectively. (From Ref. 66 by permission of American Chemical Society.)

Figure 20.11. (A) The photonic band structure calculated for an inverse opal with a refractive index contrast of 3.0/1.0. Note that there exists a full band gap between the 8th and 9th bands when the contrast in refractive index is higher than 2.8. (From Ref. 70 by permission of WILEY-VCH Verlag GmbH & Co.) (B) The transmission and reflectance spectra recorded from an inverse opal that was fabricated by templating magnetite nanoparticles against an opaline lattice of polystyrene beads of 480 nm in diameter. (From Ref. 96 by permission of WILEY-VCH Verlag GmbH & Co.)

Figure 20.12. (A) A schematic illustration of the diamond-like lattice that could be produced via self-assembly of dimers consisting two monodispersed spherical colloids. (B) The photonic band structure of this lattice, with the filling fraction of the dimeric building blocks being 34%, and their longitudinal axes being directed towards the <111> direction. The contrast in refractive index is set to be 3.01/1.00. (From Ref. 70 by permission of WILEY-VCH Verlag GmbH & Co.)

Figure 20.13. Scanning electron microscopy images of several typical examples of colloids with various nonspherical shapes: (A) peanut-shaped iron oxide colloids synthesized using a wet chemical method; (From Ref. 108 by permission of WILEY-VCH Verlag GmbH & Co.) (B) ellipsoidal polystyrene beads fabricated by stretching a polymer thin film containing spherical polymer beads; (From Ref. 107 by permission of American Chemical Society.) (C, D) dimeric and trimeric units assembled from spherical polymer beads through the confinement of physical templates. (From Ref. 13 by permission of American Physical Society.)

Figure 20.14. UV-Vis transmission spectra taken from a 3D opaline lattice (made of 175-nm polystyrene beads, and embedded in an elastomeric matrix) before (curve i) and after (curves ii-v) it had been swollen with silicone liquids of different molecular weights (and viscosities): ii) T12 (20 cSt), iii) T11 (10 cSt), iv) T05 (5 cSt), and v) T00 (0.65 cSt). (From Ref. 117 by permission of WILEY-VCH Verlag GmbH & Co.)