Photonic band gap to manipulate visible light

 
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PostPosted: Tue Aug 07, 2007 8:51 am    Post subject: Photonic band gap to manipulate visible light Reply with quote

A photonic band gap for visible light is crucial for developing more efficient miniaturised lasers, better solar cells and novel quantum optics. Alfons van Blaaderen, Marjolijn Dijkstra and colleagues of the University of Utrecht and FOM have identified a route for fabricating crystals with such a band gap. Nature Materials of February 2007 publishes their findings.

Photonic crystals feature a periodic change in the refractive index in three dimensions at the scale of the wavelength of light. This implies that photons with that same wavelength canít pass through such a crystal. Currently, no photonic crystals exist which can block visible light. Van Blaaderen, Dijkstra and colleagues have found a route for fabricating colloid crystals with the right band gap. It had been known for over ten years that diamond-like crystals of Titanium Dioxide and Zink Sulfide might be useful. Last year, theoretical calculations have shown that Pyrochloor may also be suitable.

The Dutch researchers have identified the conditions for forming a binary crystal of a diamond structure and a pyrochloor structure. These binary crystals can then be reduced to either a diamond crystal or a pyrochloor crystal. Both are in theory suitable as photonic crystals. However, the process for growing the binary crystal not only produces the desired diamond and pyrochloor binary crystal, but also two other crystals which are not suitable. The researchers propose to stimulate the growth of the right crystal by sticking a layer of bolls with the desired crystal structure to the wall of the crystallisation chamber. They still need to overcome some practical problems before they can demonstrate if their solution really works.





More information : http://www.fom.nl/live/nieuws/artikel.pag?objectnumber=55852



Story first posted: 13th February 2007.
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