Photonic Crystals

Photonic Crystals are periodic structures, there are natural examples already existing in nature, for instan ce, the Butterfly microstructure in the wings of some butterflies causes their remarkable iridescent colours. This structures reflect electromagnetic radiation as propagation through them is prohibited. The action of electromagnetic repulsion / reflection, whatever the frequency at which it occurs, is due to the fabric of the crystal. The periodicity of the crystal plays a very important role in the formation of a useful band gap. The actual width of this band gap depends on the geometry, feature size, spacing and the materials which make up the crystal. The manipulation of light with artificially manufactured photonic crystals is an important new research area.

In the figures: an example of natural band gap: butterfly wings (left); recently proposed a new structure for achieving a full three-dimensional band gap [S. G. Johnson and J. D. Joannopoulos, APL 77, 3490-3492 (Nov. 2000).] (right).

Photonic crystals are usually viewed as an optical analog of semiconductors that modify the properties of light similarly to a microscopic atomic lattice that creates a semiconductor band-gap for electrons. It is therefore believed that by replacing relatively slow electrons with photons as the carriers of information, the speed and band-width of advanced communication systems will be dramatically increased, thus revolutionizing the telecommunication industry. However, to employ the high-technology potential of photonic crystals, it is crucially important to achieve a dynamical tunability of their properties. This idea can be realized by changing the light intensity in the so called non-linear photonic cristals, having a periodic modulation of the nonlinear refractive index.

For related bibliographies, patents, and links: Visit Yurii Vlasov's Ultimate Collection of Photonic Band Gap Research Links at NEC.