System and method for fabricating optical fiber preform and optical fiber

A method of manufacturing an optical fiber preform or an optical fiber, the method comprising the steps of:

• (a) providing a glass tube and a glass core rod;
• (b) inserting the glass core rod into the glass tube to form an assembled body, the assembled body having a first leading end and an opposing second trailing end;
• (c) collapsing the glass tube on the glass core rod by heating a length of the assembled body beginning at the first leading end of the assembled body;
• and
• (d) treating a first interface gap between the glass core rod and the glass tube during collapsing of the glass tube on the glass core rod by:
• (i) establishing a vacuum pressure in the first interface gap during collapsing of the glass tube on the glass core rod proximate the second trailing end of the assembled body,
• (ii) increasing a pressure of the first interface gap by flowing a treatment gas through the interface gap for a predetermined time during collapsing of the glass tube on the glass core rod proximate the second trailing end of the assembled body, and
• (iii) re-establishing a vacuum pressure in the first interface gap during collapsing of the glass tube on the glass core rod proximate the second trailing end of the assembled body.