In this paper, we review the highly promising silica glass, fabricated as doped and undoped optical fiber for intended use in radiation dosimetry. The dosimetry techniques reviewed here, underpinned by intrinsic and extrinsic defects in silica glass, focus on Thermoluminescence (TL), Optically Stimulated Luminescence (OSL) and Radioluminescence (RL), with occasional references to the much more established Radiation Induced Attenuation (RIA). The other focus in this review is on the various materials that have been reported earlier as dopants and modifiers used in silica glass optical fiber radiation dosimeters. This article also elaborates on recently reported optical fiber structures, namely, cylindrical fibers, photonic crystal fibers and flat fibers, as well as dimensions and shapes used for optimization of dosimeter performance. The various types of optical fiber radiation dosimeters are subsequently reviewed for various applications ranging from medical dosimetry such as in external beam radiotherapy, brachytherapy and diagnostic imaging, as well as in industrial processing and space dosimetry covering a dynamic dose range from μGy to kGy. Investigated dosimetric characteristics include reproducibility, fading, dose response, reciprocity between luminescence yield to dose-rate and energy dependence. The review is completed by a brief discussion on limitations and future developments in optical fiber radiation dosimetry.
The fabrication of Tm/Al-doped silica preforms by an improved MCVD method with metal chelate precursors is discussed. Two fabrication techniques are employed, namely; simultaneous soot-dopant deposition (or standard MCVD) and stepwise soot-dopant deposition. The preforms are characterized by refractive index profiler and EPMA. The results show that the stepwise soot-dopant technique has a higher incorporation of Al2O3 and Tm2O3 as compared to the simultaneous soot-dopant method. This is due to the drawbacks of our chelate delivery system such as the temperature gradient and flow design. For the stepwise technique, the measured index difference of the preform is 0.006 with 0.8 wt% (maximum) Tm incorporated in the core.Index Terms-MCVD; metal chelate; rare earth doped silica; EPMA; refractive index
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