Reactive molten core fabrication of glass-clad amorphous and crystalline oxide optical fibers

Abstract

Described herein are glass-clad optical fibers, fabricated using a molten core fiber draw process, comprising oxide cores in the Bi2O3 – GeO2 system. More specifically, the fibers utilized a borosilicate glass cladding with core compositions in the initial preform ranging from un-reacted crystalline Bi2O3-rich (Bi2O3 + GeO2) powders to stoichiometric crystalline Bi12GeO20. Fibers drawn from the as-purchased crystalline Bi2O3-rich powders were amorphous with a transmission of about 80% at 1.3 μm. Fibers drawn from the crystalline Bi12GeO20 core contained a mixture of crystalline bismuth germanate (Bi2GeO5) and bismuth oxide (δ-Bi2O3/BiO2-x). While representing an initial proof-of-concept, this work shows that commercially-relevant draw processing can be employed to yield fibers with core composition that are very difficult to fabricate using conventional methods and that the molten core method further enables in situ reactive chemistry to take place during fiberization resulting in amorphous or crystalline oxide core fibers depending on initial core composition. Perhaps more importantly is that optical fibers possessing acentric, hence optically nonlinear, oxide crystals can be realized in a scalable manufacturing manner though further optimization is required both of the core chemistry and process conditions in order to achieve a single phase and single crystalline fiber.