Tuesday, August 22, 2006

US Patent 7094361 - Low Attenuation Optically Transparent Nanocomposites


Attenuation is a critical parameter for optical fiber construction. For long distance transmission greater attenuation requires a larger number of repeaters which greatly increases the expense of the transmission system. High purity silica glass is used in most modern fiber optics to achieve attenuation as low as 0.2 dB/km but research is ongoing to find alternative materials without the brittleness or difficulty in fabrication of high purity silica fibers. This patent is based on the discovery that for dispersed particles of a size of 10-1000 nm in a polymer matrix light is scattered in proportion to the sixth power of the particle diameter. This means that a reduction in particle diameter of ten will lead to reduction in scattering by a factor of a million. Claim 1 reads:

1. An optically transparent composite material comprising solid solution inorganic nanoparticles dispersed in a host matrix inert thereto, wherein said nanoparticles are doped with one or more active ions at a level up to about 60 mole% and consist of particles having a dispersed particle size between about 1 and about 100 nm and said composite material with said nanoparticles dispersed therein has an attenuation of less than 10 dB/cm and is optically transparent to wavelengths at which excitation, fluorescence, or luminescence of said active ions occur.