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![(a) Visible/near-IR spectra of a low-OH F-doped-silica-core optical fiber at selected times during continuous γ-irradiation at 1 Gy/s in the dark. (b) A decomposition of similar spectra of a low-OH high-purity-silica-core fiber concomitantly irradiated and recorded under identical conditions. This decomposition was achieved by first separating the red/near-IR peaks (1) from the induced absorptions at higher energies (2) by means of cut-and-try subtractions of several members of the full set of recorded spectra, of which the four displayed in (a) are corresponding examples (adapted from [44]). Superposed circles and squares in (b) represent in arbitrary units optically stimulated release of trapped positive charge from an X-irradiated a-SiO2 thin film (data from [41]).](publication/258392744/figure/fig4/AS:1089002018996232@1636649722373/a-Visible-near-IR-spectra-of-a-low-OH-F-doped-silica-core-optical-fiber-at-selected.jpg)
(a) Visible/near-IR spectra of a low-OH F-doped-silica-core optical fiber at selected times during continuous γ-irradiation at 1 Gy/s in the dark. (b) A decomposition of similar spectra of a low-OH high-purity-silica-core fiber concomitantly irradiated and recorded under identical conditions. This decomposition was achieved by first separating the red/near-IR peaks (1) from the induced absorptions at higher energies (2) by means of cut-and-try subtractions of several members of the full set of recorded spectra, of which the four displayed in (a) are corresponding examples (adapted from [44]). Superposed circles and squares in (b) represent in arbitrary units optically stimulated release of trapped positive charge from an X-irradiated a-SiO2 thin film (data from [41]).
Source publication
The natures of most radiation-induced point defects in amorphous silicon dioxide (a-SiO2) are well known on the basis of 56 years of electron spin resonance (ESR) and optical studies of pure and doped silica glass in bulk, thin-film, and fiber-optic forms. Many of the radiation-induced defects intrinsic to pure and B-, Al-, Ge-, and P-doped silicas...
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Citations
... Exposure to high-energy irradiation is known to generate free electron-hole pairs within ber optic materials. These pairs can be trapped by inherent atomic defects or impurities, forming color centers [6][7][8][9]. The formation of the color centers can induce signi cant changes in the energy-level con guration of glass, resulting in new absorption or uorescence bands [10]. ...
This study proposes a strategy for enhancing the radiation resistance of glass/fibers by introducing phase interfaces. Through phase-separation techniques and high-temperature annealing treatments, we constructed nanoscale phase interfaces engineered in erbium-ytterbium co-doped high-phosphorus silica glass with a specific density, stability level, and homogeneous distribution. Using high-resolution transmission electron microscopy, nuclear magnetic resonance, and spectroscopic analyses, we tracked the evolution of the internal microstructure of the glasses at the atomic level. The findings confirmed that annealing effectively controlled the density of the phase interfaces formed. Under 1 kGy X-ray irradiation, glasses with effective phase interfaces exhibited significant improvements in radiation-induced attenuation and photoluminescence intensity compared to pristine glasses. This indicated that effective interfacial engineering considerably enhances the radiation resistance of glasses. Furthermore, online irradiation tests on the Er³⁺/Yb³⁺ co-doped silica fibers supported this result. Compared to pristine fiber, fibers annealed for 3 hrs and annealed for 20 hrs with different phase interfacial densities showed 45% and 73% lower RIA at 1080 nm, respectively.
... Likewise the heavy or high-energy particles (e.g. alpha, and proton particles), these particles can collide with the atomic nucleus and break the atom bonds to form atomic gaps [39,40]. To determine the radiation-induced attenuation in the optical fiber, the Beer-Lambert law should be used as given by (Eq. 3) [41]. ...
... Likewise the heavy or high-energy particles (e.g. alpha, and proton particles), these particles can collide with the atomic nucleus and break the atom bonds to form atomic gaps [39,40]. To determine the radiation-induced attenuation in the optical fiber, the Beer-Lambert law should be used as given by (Eq. 3) [41]. ...
... Griscom et al. studied the gamma radiation effect of silica glass and explained mechanism [2][3][4][5][6][7]. Ravneet Kau reported that the band gap of Ba-containing borosilicate glasses reduced and Urbach energy increased after gamma radiation, and discussed the change of corresponding boron structure [8,9]. ...
Vitrification is the mainstream method for the immobilization of high-level radioactive waste (HLW). As the common matrix of vitrification, the borosilicate glass and its irradiation tolerance have been widely studied. Two kinds of borosilicate glasses were irradiated by gamma rays with absorbed doses from 104 to 107 Gy at ambient temperature. Ultraviolet and visible absorption spectra and Raman spectra were employed to characterize the microstructural changes of borosilicate glass. The Urbach energy of borosilicate glass was obtained from the absorption spectra. The noise intensity of Raman spectra with different absorbed dose were obtained. In addition, the results show that the Urbach energy is positively correlated with the noise of Raman spectra. The disorder of glasses, which was characterized by the noise on Raman spectroscopy and Urbach energy from absorption spectroscopy, increased with the absorbed dose. Finally, compared with the result of Urbach energy, the disorder of the gamma-irradiated glass can be better reflected by the noise intensity of Raman spectra. The study of the gamma radiation effects on vitrification requires more attention than before.KeywordsBorosilicate glassγ irradiationUrbach energyMicrostructure
... Earlier studies show that although high doses (>10 7 Gy) of γ irradiation cause defects in borosilicate glass, no significant changes of the mechanical properties were observed. 4,[8][9][10] Kumar indicated that the borosilicate glass is stable at a γ dose of at least 5 × 10 7 Gy. 11, 12 Kaur reported an increase of BO 3 group and nonbridging oxygen (NBO) in the γ-irradiated glass, which can lead to the loose of glass network. ...
Borosilicate glass has been extensively studied due to its unique properties of solidifying high‐level radioactive waste (HLW). However, the responses of borosilicate glass under γ irradiation are not fully understood. In this work, NBS9 and NBS10 glass were irradiated by γ‐rays at absorbed doses of 8 kGy and 800 kGy, respectively. Scanning electronic microscopy, energy dispersive X‐ray, and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) were used to observe the surface morphology and elemental distributions. The results show that the borosilicate glass remains stable until the absorbed dose was up to 800 kGy. At 800 kGy, the samples precipitate particles composed of Na and O on the surface. Na and B near the surface are significantly reduced under γ‐rays irradiation. The results indicate that the effects of γ irradiation on glass vitrification are obvious with certain accumulated doses. The changes of glass structures and elemental distributions by γ‐ray irradiation are also dependent on glass compositions.
... Among them, the most observed color center is non-bridging oxygen hole center (NBOHC) as ≡Si-O • where the H atoms are converted to their ion forms in the ≡Si−OH − . This color center can be defined as a broken bond of the O atom in the silica matrix due to ionizing radiation [32][33][34][35][36][37] and causes an absorption band at around 620 nm. Doping silica matrix with P provides Yb-doped optical fibers immune to photodarkening in high power applications [38]. ...
Ytterbium (Yb)-doped optical fibers are mainly used in the fiber laser resonator
and amplifier systems. These systems have been widely utilized for applications
in air and space, the defense industry, and the medical field. Particularly for
the applications yielding operation in harsh environments consisting of radiation,
it is essential to determine the radiation hardness of the Yb-doped optical
fibers and their long-term performance in such environments. This study analyzed
the optical properties of four different Yb-doped aluminophosphosilicate
fibers before and after Gamma irradiation. For each fiber, the effect of different
total dose values including 0.5, 1, 10, and 50 kGy were determined at
different operation wavelengths such as 495 nm, 590 nm, 685 nm, and 730
nm using radiation-induced attenuation (RIA) analysing curves. The total dose
values of 10 kGy and 50 kGy were studied to demonstrate the results under
extreme environmental conditions such as large hadron colliders (LHCs). Our
findings reveal that the formation of radiation-induced color centers (e.g. AlOHC,
POHC, and NBOHC) are highly dependent on the Yb-concentration, the amount
of excess alumina (Al2O3) compared to the phosphorous pentoxide (P2O5),
total irradiation dose and wavelength at which the respective RIA is recorded.
... There are a variety of mechanisms for the generation of color centers that lead to photodarkening at 462 nm. Generally, it is considered to be due to intrinsic stable defects in the form of "E" centers, oxygen deficiency centers (ODCs), oxygen (excess) interstitial centers, or peroxy radicals [52][53][54]. These defects have numerous absorption bands; however, of particular interest to optical pumping at 462 nm, are the "E" center absorption bands at 210 nm and 250 nm, and the 245 nm absorption band of the divalent ODC(II) [54], which has a photoluminescence band at 460 nm. ...
... These defects have numerous absorption bands; however, of particular interest to optical pumping at 462 nm, are the "E" center absorption bands at 210 nm and 250 nm, and the 245 nm absorption band of the divalent ODC(II) [54], which has a photoluminescence band at 460 nm. The peroxy radical has two absorption bands of interest at 620 nm and 258 nm [52,53,55]. Another common color center in pure silica is a partially bound oxygen atom with one free electron, which is the nonbridging oxygen hole center (NBOHC) [39]. ...
... This defect often forms as a result of optically induced breaking of a bond in a stressed multiple member Si-O ring [39]. In Ge-doped silica there are Ge(1) and Ge(2) centers with absorption bands around, respectively, 281 nm and 213 nm [53]. It is also noted that dangling bonds on the surface of the silica play a role in some laser-induced color centers [54]. ...
To date there are extensive studies of optical nonlinearities in microcavities in the near and mid-infrared wavelengths. Pushing this research into the visible region is equally valuable. Here, we demonstrate a directly pumped, blue band Kerr frequency comb and stimulated Raman scattering (SRS) at 462 nm in a silica nanofiber-coupled whispering gallery microcavity system. Notably, due to the high optical intensities achieved, photodarkening is unavoidable and can quickly degrade the optical quality of both the coupling optical nanofiber and the microcavity even at very low pump powers. Nonetheless, stable hyperparametric oscillation and SRS are demonstrated in the presence of photodarkening by taking advantage of in-situ thermal bleaching. This work highlights the challenges of silica-based, short wavelength nonlinear optics in high quality, small mode volume devices and gives an effective method to overcome this apparent limitation, thus providing a baseline for optics research in the blue region for any optical devices fabricated from silica.
... EPR studies reveal that the fundamental radiation-induced defect centres in silica systems are E'-centres [15], non-bridging-oxygen hole centres (NBOHC) [16], peroxy-radicals (POR) [17] and self-trapped holes (STH) [18]. The radiolytic process of formation of E'-centres can be presented as [ ---Si:Si ---] 0 + h + → [ ---Si⋅ + Si ---] + , where ' ---' represents the bonds to 3 bridging oxygens in the glass network, ':' represents a pair of electrons equally shared between two adjacent silicon atoms, the '⋅' indicates an unpaired electron localized in a dangling sp 3 orbital of a single silicon atom, and 'h + ' defines the hole interacting with the glass network [19]. The fission of strained Si-O-Si bonds causes the formation of NBOHC (i.e., ---Si-O⋅) defects [11]. ...
... The fission of strained Si-O-Si bonds causes the formation of NBOHC (i.e., ---Si-O⋅) defects [11]. The peroxy-radicals (POR, i.e., ---Si-O-O⋅) are formed via several pathways [11,19]. Self-trapped holes are of two types: STH 1 contains a hole trapped in a bridging oxygen network (i.e., ---Si-Ȯ-Si ---), while STH 2 comprises a hole delocalized over two bridging oxygens [11,12]. ...
... These radiation-induced defects trap the electrons that give rise to so-called "colour centres" [1][2][3]10,11,[19][20][21][22]. The absorption peak position and relative intensity of the various colour centres within irradiated soda-lime-silica glasses varies with glass-melting environment (oxidizing or reducing) [1]. ...
The development of inexpensive radiation-resistant glass is important for potential applications in displays, optics, and nuclear or space environments. This study considers the γ-ray and X-ray resistance of glasses relevant to low-cost float glass (i.e., SiO2–Na2O–CaO–MgO), modified with various concentrations (0 – 10 mol%) of Sb2O3. Various doses (0, 0.2, 2.0, and 5.0 MGy) of γ-rays from the decay of ⁶⁰Co nuclei, and X-rays generated by an X-ray fluorescence (XRF) spectrometer, have been applied to this series of Sb2O3-modified float-type glasses to study their resistance to radiation-induced damage. Irradiation leads to the formation of various defect centres (HC2, HC1, TE, E', and E⁻ types). These radiation-induced defects cause photo-darkening of the glass, which reduces its visible-wavelength optical transparency. The addition of Sb2O3 to these glasses led to reductions in the formation of radiation-induced defect-centres, combined with forbidden bandgap narrowing which led to non-linear changes in visible-wavelength absorption as a function of Sb2O3 content such that the most transparent irradiated glasses were advantageously obtained at low (0.5 mol%) Sb2O3 content. The mechanisms of defect-formation involve the creation of Sb⁴⁺-ions which assists in mitigating the effects of irradiation on the visible-wavelength transparency of the glass. The 0.5 mol% of Sb2O3-modified float glass provided a maximized concentration of Sb⁴⁺-ions upon γ-ray irradiation. Combined with the smallest changes in the UV band gap narrowing, it enabled this glass to retain the highest visible-wavelength transparency at all doses of ionizing radiation studied (0.2, 2 and 5 MGy). This work confirms the substantially enhanced radiation resistance of Sb2O3-modified float-type glasses compared to standard float glass, which could potentially be further developed towards commercialization, for example as a low-cost solution for radiation resistant applications.
... 12,17,18 Griscom proposed that upon gamma-ray irradiation, point defects and structural changes were produced in glass. [19][20][21][22][23] Mohapatra proposed that the defects, such as boron-oxygen hole center, Oxy, and HC 1 , were produced by the irradiation of electron and gamma rays, and they could disappear when the temperature was up to 500 K. [24][25][26][27][28] Barlet presented that under electron irradiation with the dose of 2 GGy, there were no changes in hardness and structure of amorphous silica. 29 Zdaniewski presented results for glass under gamma-rays irradiation, which indicated no changes in density, modulus, fracture toughness, and strength at the absorbed dose of 10 6 Gy. 30 With electron irradiation, changes in the hardness of glasses were separately reported by Chen and Mir. ...
Vitrification is a kind of glass that can solidify high‐level radioactive waste (HLW). As the basic material of vitrification, borosilicate glass was studied extensively. To keep HLW away from the biosphere, the tolerance of borosilicate glass to irradiation is important. In this work, various samples of borosilicate glass with different compositions were irradiated with gamma rays at ambient temperature to study their stability. The hardness, moduli, and microscopic changes on surfaces of the borosilicate glasses were measured at specific absorbed doses. Upon the gamma irradiation, the structural changes on surfaces of borosilicate glasses were identified, which were strongly influenced by the composition of borosilicate glasses. The results demonstrate that gamma irradiation, as well as beta irradiation, might strongly influence the properties of vitrification. The irradiation effects on vitrification induced by gamma irradiation should be paid more attention to than before.
... The hole can be paired with another electron to form new atomic bonds, resulting in the rearrangement of the atomic structure. If the radioactive rays consist of heavy or high energy particles, the particles could collide with the atomic nucleus and break the atom bonds to form an atomic gap [34,35]. The existence of broken holes, reconstructed atomic structures, and atomic gaps increase the loss of fiber materials while affecting the refractive indexes. ...
Optical fibers are being widely utilized as radiation sensors and dosimeters. Benefiting from the rapidly growing optical fiber manufacturing and material engineering, advanced optical fibers have evolved significantly by using functional structures and materials, promoting their detection accuracy and usage scenarios as radiation sensors. This paper summarizes the current development of optical fiber-based radiation sensors. The sensing principles of both extrinsic and intrinsic optical fiber radiation sensors, including radiation-induced attenuation (RIA), radiation-induced luminescence (RIL), and fiber grating wavelength shifting (RI-GWS), were analyzed. The relevant advanced fiber materials and structures, including silica glass, doped silica glasses, polymers, fluorescent and scintillator materials, were also categorized and summarized based on their characteristics. The fabrication methods of intrinsic all-fiber radiation sensors were introduced, as well. Moreover, the applicable scenarios from medical dosimetry to industrial environmental monitoring were discussed. In the end, both challenges and perspectives of fiber-based radiation sensors and fiber-shaped radiation dosimeters were presented.
