Patent ID: 6603903
Filing Date: 2003-08-05
Classification: G02B

Abstract:
The method of writing a strong grating in an optical fiber comprising the steps of:preparing a core/cladding fiber with a germanium doped, photosensitive cladding; heating the fiber during stretching with a moving flame that imparts substantially no OH and oxidizes the fiber to a selected level; stretching the fiber during heating until a waist region with a vestigial core is formed; diffusing a photosensitizing gas into the waist region at elevated pressure; maintaining the diffusion into the waist while writing a grating in the waist with scanning actinic illumination; balancing the photochemistry by adjusting illumination intensity and scanning velocity to achieve a [Ge2+] fraction of 0.1 or less; and maintaining the illumination until the photo-induced index change reaches a selected level.