Two step etching process for an optical fiber preform

摘要

This invention relates to a method of preparing an optical fiber preform with the preform having a uniform refractive index profile for the deposited oxide material that ultimately forms the optical fiber core. One embodiment of the invention relates to a process for preparing an optical fiber preform comprising the steps of etching a substrate a first time to remove a portion of a deposited oxide material from the preform by using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to create a fluorine contamination layer in the remaining deposited oxide material; and etching the preform a second time using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to remove the fluorine contamination layer without any substantial further fluorine contamination of the remaining deposited oxide material. Further embodiments relate to similar processes.