US Patent 7657142 - Manufacture of nanoparticle optical fiber

http://www.freepatentsonline.com/7657142.html

Telecommunication systems often employ glass fibers doped with ions to amplify optical signals. Nanoparticles have been proposed to assist in such doping but have been subject to oxidation which limit their effectiveness. This patent from Alcatel-Lucent discloses a method to avoid such oxidation. Claim 1 reads:

1. A method for manufacturing an optical fiber, comprising:

creating a preform, containing nanoparticles bearing an active element including at least one recess proximate to at least part of the nanoparticles; and

introducing a non-oxidizing gas into the recess, forming the fibers of the preform, thereby limiting the chances that the nanoparticles in the preform will oxidize.