PRODUCTION OF OPTICAL FIBER PREFORM

摘要

PURPOSE:To provide a process for producing an optical fiber preform usable for the production of e.g. optical fiber laser and fiber for optical amplifier. CONSTITUTION:The optical fiber preform to be produced by this process is composed of a core and a clad and contains a dopant compound doped in the core. The present invention is characterized in that a glass film composed mainly of Si and O, containing the dopant compound and having a refractive index higher than that of a clad-forming glass tube is formed on the inner wall of the glass tube by sol-gel process, and the product is collapsed to form the core. Particularly preferable embodiment of the invention is the addition of a rare-earth element compound as the dopant compound. A dopant such as rare-earth element can uniformly be added to the core at high concentration.