Ludwigshafen, Germany--In a three-year EU-sponsored project, BASF is working with industry and academic partners—Hanover Laser Center, Thales Aerospace Division, Photon Design Ltd., the Technical University of Denmark and the Ecole Nationale Supérieure des Télécommunications de Bretagne—to develop photonic crystals they say will revolutionize telecommunications.
By the end of 2008, the partners in the EU "NewTon" project expect to have developed the first functional components of this new technology. The long-term goal is to use three-dimensional photonic crystals as construction elements in telecommunication. Half of the project is being funded by the European Union.
BASF and its partners are developing a photonic crystal capable of reflecting only single colors of the white light depending on the observation angle. The production of these crystals is based on aqueous dispersions, a key competence of BASF. These dispersions contain polymer spherical particles measuring about 200 nanometers which, when the fluid evaporates, are forming a homogeneous protective film as it is expected with the paints. Depending from the chemical structure of the polymer particles they can also arrange themselves into a regular lattice structure, forming a crystal.
"A structured three-dimensional photonic crystal could be the key component for a compact optical semiconductor or even for an all-optical routing processor," said Reinhold J. Leyrer, project leader in BASF's Polymer Research division. "Converting optical signals into electrical signals would then be superfluous."
The challenge facing the Ludwigshafen scientists is to enlarge the polymer particles contained in the dispersions to 1000 nm in such a way, that they all have exactly the same diameter. Using emulsion polymerization, they also apply an additional structure measuring less than 20 nm onto the polystyrene particles. The intention is to develop the most stable possible, large volume, three-dimensional crystal into which one of the project partners will then introduce the desired structure—the so-called "defects."
Light at certain wavelengths then travels along these defects and even around sharp corners: the photonic crystal then acts as a photoconductor and takes the control over the propagation of light. The resulting structured crystal lattice is used in the further manufacturing process as a template, as the scientists call it. The spaces between the polymer spherical particles in the crystal lattice are filled with silicon. The researchers then "burn" the polymer particles out of the lattice. The result: a stable structure that is a mirror image of the original crystal. Crystals of this type could be used as components for an all-optical routing processor in telecommunications.
For further information about this project, please click on project newton.