METHOD TO PREVENT CRACKS IN OPTICAL FIBER PREFORMS

摘要

The present disclosure provides optical fiber preforms formed from core canes having large core-clad ratio, intermediate core-cladding assemblies, and methods for making the preforms and core cladding assemblies. The preforms are made with capped core canes. The capping material has a coefficient of thermal expansion less than the coefficient of thermal expansion of the core cane and more closely matched to or lower than the coefficient of thermal expansion of the surrounding cladding monolith in a cane-in-soot process. Presence of the cap reduces stresses that arise from differential thermal expansion of the core cane and cladding materials and leads to preforms having low defect concentration and low probability of failure during subsequent thermal processing steps.

主权项

1. A core-cladding assembly comprising:
a porous soot cladding monolith, said porous soot cladding monolith including a first porous cladding glass layer surrounding an internal cavity, said porous soot cladding monolith comprising a first material having a first coefficient of thermal expansion; a first glass body having a portion positioned in said internal cavity, said first glass body comprising a second material having a second coefficient of thermal expansion, said second coefficient of thermal expansion differing from said first coefficient of thermal expansion; and a second glass body having a portion positioned in said internal cavity, said second glass body comprising a third material having a third coefficient of thermal expansion, said third coefficient of thermal expansion differing from said second coefficient of thermal expansion.