Development of a new doping principle for manufacturing of rare earth ion activated silica preforms for optical fibers and study of their spectroscopic properties

A new doping principle for the fabrication of optical waveguides has been proposed and developed. The principle involves the use of a “building block” approach, when a doping precursor, which includes some or all chemical elements necessary for the formation of an optical waveguide, also contains optically active rare earth ions that are spatially organized in a desired manner on a molecular level.; This research has been concerned with the use of precursors that potentially have large minimum distances between rare earth ions in order to increase resulting minimum distances in the final glass made from such precursors and therefore decrease the rate of cooperative energy transfers between rare earth ions leading to quenching of luminescence.; Aluminosilicate molecular sieves, zeolites X and Y, with rare earth loading levels not exceeding 16 ions per unit cell in the network of small cages have been proposed and investigated as “building block”, large minimum distance precursors for the fabrication of silica optical fibers.; Zeolite derived optical preforms and fibers with ultra-high rare earth concentrations up to 1.2 · 1021 ion/cm 3 have been fabricated for the first time using methods developed in this work. A new acid-free low-water neutral pH sol-gel process has been developed for the deposition of sol-gel films containing zeolite powders.; Luminescent properties of neodymium doped zeolite derived preforms have been studied as a function of the total rare earth concentration and levels of rare earth loading of zeolites. Luminescent properties of zeolite-doped sol-gel films at various stages of vitrification have also been studied to evaluate rare earth ion quantum yield and the ion arrangement at different fabrication stages.; It has been demonstrated that the lifetime of the Nd3+ metastable level in dehydrated unsintered zeolite-doped sol-gel films strongly increases when zeolite loading becomes less than 16 neodymium ions per unit cell in the network of small pores in both zeolite X and Y. It has also been determined that zeolites with rare earth loading levels between 12 and 25 ions per unit cell allow fabrication of optical preforms with luminescent properties comparable to those obtained by other known approaches.