Mechanical Reliability of UV Irradiated Fibers: Application to Bragg Grating Fabrication

Abstract

Intra core fiber grating components [1] like reflection-, transmission-, and loss filters play a major role in telecommunication [2] and sensor networks [3]. The reliability of such components is crucial since survival times of up to 50 years are needed. The fiber strength that characterizes the mechanical reliability is determined by the distribution of intrinsic and extrinsic defects, called flaws. Intrinsic and extrinsic flaws are related to defects in the silica bond structure and surface microcracks due to fiber manufacturing, respectively. UV absorption in the fiber core creates new intrinsic defects leading to a core tension increase due to compaction of the glass structure [4]. In this paper we report on the mechanical reliability of fibers irradiated by UV light using the side exposure technique [5]. Homogeneous excimer laser irradiation reduces the mechanical resistance considerably depending on the fluence per pulse [6, 7] and the laser wavelength [8]. With increasing pulse energy density the mechanical resistance is lowered. In contrary, homogeneous CW irradiated fibers show almost the same fiber strength as compared with pristine fiber [9].