Light Manipulation with 3-Dimensional Templated Photonic Crystals

Dr. Sergei G. Romanov and Prof. Dr. Clivia M. Sotomayor Torres

Institute of Materials Science and Department of Electrical Engineering, University of Wuppertal, 42097 Wuppertal, Germany

The photonic energy band structure, resulting from a suitable periodic modulation of dielectric properties in a solid, makes it possible to control the propagation and emission of light without dissipation. To realise the full extent of these possibilities, electromagnetic waves have to be confined in 3-dimensions. Three-dimensional crystalline packages of silica or polymeric balls (synthetic opals and similar structures) as well as their replicas, i.e. inverted opal, have been recognised as suitable models of 3-dimensional photonic crystals. In our lecture the following topics related to experimental studies of templated opal-based photonic crystals operating in the visible range of spectrum will be discussed:

1. Technological aspects of the fabrication of 3D opal-like and opal-templated photonic crystals. Examination techniques and results.
2. Bragg diffraction from silica- and polymeric-based photonic crystals, mapping of corresponding anisotropic photonic bandgap structures. Enhancement of the photonic stop-band (bandgapwidth enlargement, bandgap dispersion smoothening) by means of infilling and coating opals with high refractive index materials (S, TiO₂, CdS, InP, GaP) and inversion of opals.
3. Comparison of stop-band characteristics of bulk and thin-film opal-like photonic crystals
4. Design and testing of organic-inorganic opal-based photonic crystals (e.g. opal-TiO₂-polymer-dye/rare earth ion structures).
5. Peculiarities of light propagation in photonic crystals with double PBG structure (GaP-opal/Air-opal).
6. Probing the density of photonic states in opal-like photonic crystals.
7. Self-focusing of the emission from opal-like photonic crystals, focusing enhancement with the increase of the refractive index contrast. Modelling of this effect using the superprism approach.
8. Probing the changes in the spontaneous emission rate of emitters embedded in photonic crystals.
9. Comparison of emission from wide (laser dyes) and narrow (rare earth ions) band emitters embedded in photonic crystals.
10. Prospective opal-based device structures.

NB. Some parts of experimental work to be described have been performed in collaboration with the University of Salford (Prof. M.E. Pemble), the University of Glasgow (Prof. R. M. De La Rue), the Ioffe Institute of St. Petersburg (Prof. Y.A. Kumzerov)