OPTICAL FIBERS AND PREFORMS WITH ONE STEP FLUORINE TRENCH AND OVERCLAD AND METHODS FOR MAKING THE SAME

摘要

A method is provided that includes: forming a low-index trench region with a first density; forming an inner barrier layer comprising silica around the trench region at a second density greater than the first density; depositing silica-based soot around the first barrier layer to form an overclad region at a third density less than the second density; inserting a core cane into a trench-overclad structure; forming an outer barrier layer comprising silica in an outer portion of the overclad region at a fourth density greater than the third density; flowing a down dopant-containing gas through the trench-overclad structure to dope the trench region with the down dopant, and wherein the barrier layers mitigate diffusion of the down-dopant into the overclad region; and consolidating the trench-overclad and the core cane.

主权项

1. A method for forming an optical fiber preform, comprising:
depositing silica-based soot on a bait rod to form a low-index trench region, wherein the silica-based soot is deposited such that the trench region has a first density; forming an inner barrier layer comprising silica around the trench region, wherein the inner barrier layer has a second density greater than the first density; depositing silica-based soot around the first barrier layer to form an overclad region of the optical fiber preform at a third density, wherein the second density is greater than the third density; removing the bait rod from a central channel of a trench-overclad structure that comprises the trench region, the inner barrier layer and the overclad region; inserting a core cane into the central channel of the trench-overclad structure after the step for removing the bait rod; forming an outer barrier layer comprising silica in an outer portion of the overclad region, wherein the outer barrier layer has a fourth density greater than the third density; flowing a down dopant-containing gas through the central channel of the trench-overclad structure after the step for inserting the core cane, wherein the trench-overclad structure is sufficiently heated to dope the trench region with the down dopant, and further wherein the barrier layers mitigate diffusion of the down dopant into the overclad region; and consolidating the trench-overclad structure and the core cane after the step for inserting the core cane into the optical fiber preform.