Behavior of fibre Bragg gratings under high total dose gamma radiation

Abstract

We report on the effect of MGy dose level γ-irradiation on the parameters of fibre Bragg gratings intended for sensing applications. The γ-radiation sensitivities of gratings written with near-UV 330 nm light in hydrogen loaded Ge-doped fibres and of a grating written in a N-doped fibre were found to be higher than that of gratings written in a 10 mol.% Gedoped fibre without hydrogen loading. In the former cases, changes in the amplitude and the width of the Bragg peak were observed during γ-irradiation while no change was observed in the latter case. For the grating written in the Ndoped fibre, the radiation-induced shift of the Bragg peak did not saturate while for gratings written in hydrogen-loaded Gedoped fibres it saturated to a higher level than for gratings written in unloaded Ge-doped fibre.

Stabilization of fiber Bragg gratings against gamma radiation

“…A lower values of 20-50 pm of the Bragg peak shift in the red direction were reported in subsequent publications [7][8][9][10], where careful in-situ measurements of grating spectra were applied. It is known that y-irradiation (60CO source) of a silica glass doped with 11 mol.% of Ge02 creates the same type of paramagnetic defects related to the photosensitivity effect as 248 nm UV -light does [11].…”

Bragg wavelength shift for irradiated polymer fiber Bragg grating

“…PFBG was attributed to its inherent properties such as sensitivity to small changes, small size, passive nature and it has immunity against high voltage [5]. Others investigated the effect of the different types of ionizing radiations on the response of fiber sensors [7][8][9][10] in order to be used as radiation-dosimeters. Among those fiber sensors, the FBG has been used in applications related to fusion installations, in the telecommunications in space applications, terrestrial nuclear facilities and in nuclear reactors [10][11][12].…”

New nanosecond Q-switched Nd:VO4 laser fifth harmonic for fast hydrogen-free fiber Bragg gratings fabrication

“…In order to shorten the time of processing optical fibers, it is desirable to avoid hydrogen-loading. Additionally, the ability to write strong gratings in standard-telecommunications fiber would also be of great benefit for a variety of applications in the sensing industry for nuclear applications, which is wary of the presence of residual hydrogen in fibers after grating inscription, despite annealing [10]. It is also known that writing with high peak intensity and hydrogen-loading can significantly reduce the mechanical strength of FBGs [11].…”