Study of doping process influence the fiber's photosensitivity

Abstract

This study indicate that the Fluorine doped would influence the fiber's photosensitivity. The Boron doped would increase it distinctly when the dope content reach 5%. Then it would get the saturation on about 30%. Introduction The discovery of photoinduced, refractive index grating formation within the Ge-doped core of a silica optical fiber by Hill et al. [1] in 1978 which began an intense period of research activity in the area of photosensitive defects in optical fiber. Fiber gratings written into photosensitive fiber by UV holographic techniques are attracting considerable attention due to their broad range of potential application in photonic devices and optical communications such as dispersion compensation, and sensors [2]. Photosensitive fibers are based material for writing optical fiber grating. Germanosilicate glass fibers have a well known photoinduced refractive index change initiated by UV light at wavelengths near 240nm and this phenomenon has been used to form reflection gratings at telecommunication wavelengths [3]. Based on the PCVD process, the fiber's refractive index profile and the doping content can be controlled accurately. In fiber making process, the Ge,B and F are doped into the fiber. The absorption band located near 242 nm [4] is connected to defect centers in the germanosilicate matrix. The fiber's attenuation @630nm could be used to speculate the fiber's defect content. Change the fiber's doping content, the fiber's photosensitivity could be changed obviously.