Open Access
Add to BibSonomy
Abstract
Magneto-optical properties of Bi-doped silica optical fibers (BDF) and single mode fiber (SMF) before and after irradiation (0-3.0 kGy) are investigated. BDF is prepared by the atomic layer deposition (ALD) technique combined with the conventional modified chemical vapor deposition (MCVD) process. Before irradiation, the Verdet constant of BDF (1.64 rad/(Tm)) is 27.13% larger than that of SMF (1.29 rad/(Tm)) at 980 nm. Because the Verdet constants of both of them are positive values, this implies diamagnetic behaviors of fiber sample materials. After irradiation, the Verdet constant of SMF keeps increasing with the increase of radiation doses (0-3kGy). However, in the same radiation dose range, the Verdet constant of BDF is decreased first and then increased. It is decreased with the increase of gamma irradiation in the low-dose range (<0.3 kGy). Especially, the Verdet constant of BDF in 0.3 kGy is of a negative value and the Faraday rotation of it is anti-clockwise, which means the fiber sample exhibits paramagnetic material properties. When the radiation dose is from 0.3 to 3 kGy, the Verdet constants of the BDF is increased. Furthermore, in a 3 kGy treatment, the Verdet constant of BDF (1.87 rad/(Tm)) is 23.84% larger than that of SMF (1.51 rad/Tm), and is 44.96% larger than that of SMF without irradiation treatment. The novel change of magneto-optical characteristics of the BDF sample may mainly result from irradiation-induced valence state change of bismuth ions.
© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
1. Introduction
Current sensor based on Faraday effect has been extensively investigated in the field of current measurement for its resistance to electromagnetic interference, good insulation, wide measurement range, etc. [1,2] In practical applications, the performance of current sensor is limited by magneto-optical material. In paramagnetic materials, Faraday rotation of linearly polarized light is larger than that in diamagnetic materials, but sensors that use paramagnetic materials as magneto-optical media have the drawback of temperature dependence [3,4]. Bismuth, which can improve both sensibility and stability of current sensors, due to its high Verdet constant and small intrinsic temperature dependence, has been widely studied [5–7]. Most previous investigations on bismuth doping materials mainly focus on glass and crystal [8,9]. However, these materials are higher cost, bigger size, and relatively poor transmission. For comparison, doping optical fibers have many advantages, such as immunity to electromagnetic interference, light weight, easy integration, high sensitivity [10–12].
Many effects have been done in order to further improve Verdet constant, including gamma-ray radiation. Y. Kim, et al. [13,14] have reported that radiation is an effective way to further improve Verdet constant of silica optical fibers because of the formation of radiation induced defects. Previous literature has also reported that radiation induces photoluminescence enhancement of Bi-doped fibers [15]. However, radiation effect on magneto-optical properties of Bi-doped materials has not yet been reported.
In this paper, Verdet constants of BDF before and after irradiation are studied, and a magneto-optical system is built up to measure Verdet constant of BDF. In addition, the radiation induced magneto-optical properties change is also studied.
2. Experimental section
Bi-doped silica optical fibers are prepared via modified chemical vapor deposition (MCVD) combined with ALD (TFS-200, Beneq Inc., Finland.). The preparation process has been reported previously [15,16]. As is shown in Fig. 1, the fiber core and cladding diameters were approximately 13.10 and 123.47 µm, respectively. The refractive index difference of the core and cladding, analyzed by an optical fiber index analyzer (S14, Photon Kinetics Inc., USA), is approximately 0.66%, and the cross-section is also shown in the upper righter corner of Fig. 1.
The element compositions of the doped materials are tested using an EPMA. Concentration of Bi, Al, Ge, O, Si elements are 0.26, 0.040, 6.0, 66.0 and 28.0 mol%, respectively, and the result shows that Bi ions are successfully doped into fiber core section.
Irradiation is performed with gamma-ray from a Cobalt-60 radiation source (Irradiation Center at Medical College of Soochow University). The SMF and BDF samples are irradiated with cumulative doses approximately 0.2, 0.3, 0.5, 0.8, 1.0 and 3.0 kGy at room temperature. The radiation dose rate is 0.2 Gy/s.
Absorption spectrum is measured by cut-back technique with white light source and optical spectrum analyzer (OSA, Yokogawa AQ-6315A) in 600 to 1600 wavelength region.
Faraday effect is a magneto-optical phenomenon that polarization plane of linearly polarized light is rotated with an angle in magnetic field. The rotation is originated from the different dispersions in right circularly polarized light (${n_ + }$) and left circularly polarized light (${\textrm{n}_ - }$), and phase difference between the right circularly polarized light and left circularly polarized light causes Faraday rotation after a distance L [17,18]. The Faraday effect can be expressed as Eq. (1) [19,20]
where $\theta $ is Faraday rotation angle, B is the strength of magnetic field, L is the length of fiber in magnetic field and V is Verdet constant.The extinction ratio (ER) of light can be measured by adding a new rotatable polarizer at the point to be measured [21]. Light transmits through the added polarizer and onto a power detector. Rotating polarizer to get the maximum and minimum power, and ER can be calculated by Eq. (2).
A system is setup for the measurement of Faraday rotation angle in order to accurately measure the Verdet constants of fiber samples, as is shown in Fig. 2. The system mainly consists of four parts, including laser source, polarization controller, solenoid, and analyzer part. Here the polarization control part is to obtain high quality linearly polarized light, which consists of a collimating lens, two polarizers (P1 and P2) and a quarter-wave plate. Firstly, laser beam from fiber-coped Fabry-Perot laser diode (S1FC980, S1FC1310, S1FC1550, Thorlabs, USA), is launched into collimating lens by optical fiber patch cord. Secondly, the light passes through P1, quarter-wave plate and P2. ER of light passed through P1 is measured to be less than 35 dB and is non-uniform at every direction because of the existence of birefringence in fiber patch cord. To get uniform and high quality polarized light at any direction, a quarter-wave plate is added behind the first polarizer. The ER of light passed through quarter-wave plate is measured to be 0.35 dB. And the ER of light passed through P2 is measured above 37 dB. The polarization state is shown in the upper part of Fig. 2. Thirdly, linearly polarized light after the second polarizer is focused on optical fiber using a×10 microscope object.Linearly polarized light is converted into elliptically polarized light for the existence of birefringence in fiber, which influences the precision of results. The cutoff wavelength of BDF is larger, which means high-order modes can be transmitted in the fiber. In order to decrease influence of higher-order modes, optical fiber sample in magnetic field is supposed to be short in length and prevented from bending or twisting. According to the magnetic field distribution along the solenoid axis [22], DC current is set to be below 5.0 A and the length of BDF under magnetic field is 30 cm. In the region, the intensity of the magnetic field is relatively stable. Finally, the polarization states of emergent light can be detected by stokes polarimeter (PAX5710, Thorlabs, USA). The accuracy of the stokes polarimeter is 0.01 degree. And change of polarization states can be described in the Poincare Sphere. The intensity of output light beam is nearly Gaussian distribution, which means output polarized light is mainly of fundamental mode (LP01).
3. Experimental results and discussion
ER and Faraday rotation of SMF (Coring SMF-28e) and BDF with different radiation doses treatment are measured, and the light source is 980 nm here. The ER of BDF under different irradiation doses treatment are shown in Table 1. While measuring ER, Faraday rotation and Verdet constant of the fibers, multiple measurements and average calculation are carried out to avoid systematic error and fluctuation.
Table 1. ER of output polarized light from BDF with different irradiation doses
Before irradiation, the ER of SMF is 23.3 dB, which is larger than that of BDF (18.0 dB). After radiation, the ER of both SMF and BDF are changed, as shown in Fig. 3. The higher radiation dose is, the lower ER is, which means that radiation influences properties of birefringence and eventually increases the random linear birefringence in fiber.
Faraday rotations of fiber samples are proportional to the intensity of the applied magnetic field, and from β1 to β7, as shown in Fig. 4. Before irradiation, the slope of rotation angle of BDF (β2) is larger than that of SMF (β1), as shown in the gray area of Fig. 4. After irradiation, changing trend of the slope of rotation angle from β2 to β4 is clockwise, and it is anti-clockwise from β5 to β7.
The slope of rotation angle to the applied magnetic field determines Verdet constants of the corresponding fibers. For the Bi-doped fiber, before irradiation, its Verdet constant (1.64 rad/(Tm)) is 26.0% larger than that of SMF (1.29 rad/(Tm)), and then Verdet constant value is positive, which shows that the BDF fiber material is of diamagnetic properties. After irradiation, Verdet constant of SMF remains be increased with the increasing of radiation doses. However, that of Bi-doped fibers are decreased in low radiation doses (<0.3 kGy). Especially after 0.3 kGy irradiation treatment, Verdet constant of Bi-doped fiber is negative value, which shows that the Bi-doped fiber material is of paramagnetic property. And then its Verdet constant value is positive and increased with the increasing of radiation doses, from 0.5 to 3 kGy. Especially after 3.0 kGy irradiation treatment, Verdet constant of Bi-doped fiber is 1.87 rad/(Tm), which is 23.84% larger than that of SMF (1.51 rad/(Tm), and is 44.96% larger than that of SMF without irradiation treatment.
SMF radiated with different doses under 118 mT magnetic field is measured. Verdet constant of SMF increases with increasing of radiation doses, as shown in lower right corner of Fig. 5.
For the SMF, with the increasing of irradiation doses, the Verdet constant becomes essentially constant because the Ge-related defects tend to be saturated. Meanwhile, for the doped fibers, the Verdet constant is still increased, which means that the increasing of Verdet constant may result from the doped ions role, as also reported in previous study [23]. Here, for the BDF irradiated treatment, the change of Verdet constant may mainly results from Bi ions role. In the Bi-doped fiber materials, Bismuth atom, with 6s26p3 out electronic shell, is easy to lose three electrons in 6p layer then becomes to Bi(3+) (6s2). Bi(3+) is of intense s2-sp electron jumps, which involving 1S0→1P1, 3P1 transition. With applied magnetic field, the main interaction between ions and applied magnetic field is Zeeman splitting interaction. In this process, there are many splitting energy level at excited level with different values of ${m_L}$ (${m_L}$: magnetic quantum numbers). Inequality on the transition of $\Delta {m_l} ={\pm} 1$, which is corresponding to transition of left and right circularly polarized light, could induce different dispersions in right circularly polarized light (${n_ + }$) and left circularly polarized light (${\textrm{n}_ - }$), and finally makes contribution to Faraday rotation, as expressed in Eq. (1).
However, bismuth may take the form of multiple valence states in fiber, such as Bi0, Bi(1+), Bi(2+), Bi(3+), Bi(5+) [24–27]. Furthermore, among various valence states may convert to each other under irradiation treatment [15]. These different valence states ions have different out electronic shell structures. Bi(3+) (6s2) and Bi(5+) (5d10) ions, which have no unpaired electron in the out electronic shell, show diamagnetic properties. On the contrary, Bi0 (6s26p3), Bi(1+) (6s26p2) and Bi(2+) (6s26p1) show paramagnetic properties because of unpaired electrons in 6p layer, which makes contribution to intrinsic magnetic moment. Therefore, Verdet constant of BDF can be determined by ${V_{dia}}$ and ${V_{para}}$, as described in Eq. (3). There may be impurity monovalent or other valence states (${V_{para}}$) in the un-irradiation BDF. However a large number of trivalent bismuth ions (${V_{dia}}$) existed in BDF play a major role. Therefore, BDF without irradiation exhibits diamagnetic properties, as shown in the left of Fig. 6.
Under irradiation, Verdet constant of SMF is increased with the increasing of radiation doses. This phenomenon drives from radiation induced germanium-related defects such as self-trapped hole center (STH), germanium electron center (GEC) [28–31]. The electron-trapped centers associated with fourfold coordinated germanium ions and STHs of bridging oxygen between Ge ion and Si ion are generated. For higher weight of germanium atom compared with silica, germanium ions are easy to capture free electrons, which come from the irradiation-induced role, that is these radiation-induced electron transformation results from bridging oxygen to a fourfold coordinated germanium ions, which finally lead to Verdet constant increased in irradiated SMF.Contrast black line to red line in Fig. 5, non-incremental changing trend of irradiated BDF may derive from irradiation effect on bismuth ions. Valence states of bismuth ions convert to each other in different radiation doses. Under low-doses irradiation (0.2-0.3 kGy), electrons are generated from bridging oxygen. In our previous study, we detected many radiation-induced defect centers in the irradiated Bi-doped fiber samples by electron spin resonance (ESR) [15]. Bi(3+) and Bi(5+) ions with big mass and high polarizability [32], are more likely to capture electrons compare with germanium ions. So we suppose that Bi(5+) ions may capture free electrons, which originates from defect centers, such as GECs, and transforms into Bi(3+), Bi(1+) or Bi0, as shown in Fig. 7(a). In this process, the diamagnetic behavior overlaps paramagnetic behavior. Consequently, the Faraday rotation is anti-clockwise and shows opposite phenomenon, as shown in the middle circle of Fig. 6.
With the increasing of irradiation doses from 0.5 to 3.0 kGy, low-valence-state bismuth ions are of high energy and likely to lose electrons under gamma-ray effect, as shown in Fig. 7(b). In this process, irradiation generates electron-hole pairs which lead to the conversion from bismuth ions with low valence states to high valence states [33]. High valence states ions show diamagnetic properties while the low valence ions show paramagnetic properties, so the magneto-optical properties of the fiber change, as shown in the right circle in Fig. 6. Combing with irradiation effect on host materials, ${V_{dia}}$ related bismuth ions in BDF contribute to final enhancement of Verdet constant of BDF.
To further prove conversion of valence states under irradiation, absorption spectra of BDF before and after irradiation (0.3 and 0.5 kGy) are measured. There have been many investigations about absorption spectra of bismuth-doped materials. Previous report shows that absorption peaks of Bi(3+) and Bi(2+) exist in the ultraviolet or violet regions [34]. Firstov et al. and Sokolov et al. demonstrate the near IR luminescence and optical transitions properties of different Bi(5+) ions and Bi clusters [35,36]. Fujimoto J. et al. assigned absorption peaks of Bi(5+) at 300, 500, 700, 800 nm to transitions from 1S0 to 1D2, 3D1, 3D2, and 3D3 [37]. Absorption peaks of Bi(1+) at 500, 700, 800 and 1000 nm driving from transitions from ground state 3P0 to 1S0, 1D2, 3P2 and 3P1 was discussed by Meng X. et al [25,26]. And Ping M.Y. et al. reported that absorption peak at 850 nm is attributed to the transition in Bi0 from 4S3/4 to 2D3/2 [38]. Then it is controversial to regard the 850 nm absorption peak as Bi0. The absorption peak at 850 nm also may be caused by some wave-guiding phenomenon. For strong absorption of BDF, the spectrum is from 600 to 1600 nm. As is shown in Fig. 8, before irradiation, there are main absorption at 700, 800, 1000 band and 1377 nm. Besides peak at 1377 nm is obviously produced by OH-, the others drive from bismuth ions. Absorption peaks at 700 and 800 nm correspond to absorption of Bi(5+) and Bi(1+). And 1000 nm absorption band proves appearance of Bi(1+) in BDF. Especially, the intensity of 700 nm is stronger than absorption spectrum previously reported [34], which may mainly result from the transition of few Bi(1+) from 3P0 to 1S0. After irradiation, owing to radiation-induced attenuation, higher radiation doses result in the increase of the background attenuation and OH- absorption, as shown in the right part of Fig. 8. Under 0.3 kGy, the absorption peak at 700 nm is increased obviously, which results from the conversion of Bi ions from high valence states to Bi(1+). And there is a new absorption at 850 nm, which can prove the appearance of Bi0 under 0.3 kGy radiation. Under 0.5 kGy, although background attenuation is increased, absorption at 700 nm is decreased and absorption at 850 nm disappeared. This phenomenon witnesses that concentration of Bi(1+) and Bi0 is decreased then convert to high valence states.
Verdet constants of BDF irradiated with 3.0 kGy at wavelength of 980, 1310, 1550 nm are shown in Table 2. Verdet constants of each fiber are measured for multiple times to avoid systematic error and fluctuation. In Fig. 9, the Verdet constant of SMF and BDF at 980, 1310 and 1550 nm wavelength are plotted. The Verdet constant is inversely proportional to the wavelength according to Eq. (1). The curve is polynomial fitting of corresponding wavelength dependent point. The wavelength dependence of measured Verdet constants is described well within experimental error. Before the BDF is radiated its Verdet constant is positive value. After irradiated with 0.3 kGy BDF’s Verdet constant is negative value, which shows paramagnetic property. However, when the irradiation doses are increased the BDF’s Verdet constant become positive value. And then after the irradiation dose is more than 0.3 kGy, its Verdet constant value become larger. Especially Verdet constant of BDF with 3.0 kGy is 44.25% higher than that of SMF, as shown in Fig. 9. Those show that the BDF is of diamagnetic property. Here these exists a kind of transformation process of magneto-optical property, which may results from the valence states conversion of bismuth ions. For the bismuth-doped silica optical fiber, irradiation treatment obviously affects the valence states structure of bismuth ions. There is an intense s2-sp electron jump after the BDF is irradiated. Those result in the valence states conversion of bismuth ions. What is more, magneto-optical property of the BDF could be obviously improved and the sensibility of current sensors is enhanced.
Table 2. Verdet constant of BDF irradiated with 3.0 kGy
4. Conclusion
We investigate the magnetic-optical properties of BDF before and after irradiation at 980, 1310 and 1550 nm and built up an experimental system to measure it. Before irradiation, the Verdet constant of BDF is larger than that of SMF at any wavelength and Faraday rotation of them are clockwise proving their diamagnetic properties. And Verdet constant of BDF is 27.13% larger than that of SMF at 980 nm. After irradiation, Verdet constants of SMF remain increased with increasing radiation doses. However, Verdet constants of BDF are decreased with radiation dose increasing from 0 to 0.3 kGy. Especially, under 0.3 kGy, BDF is of anti-clockwise Faraday rotation and is of paramagnetic properties. Verdet constant of BDF is positive values and is increased with the radiation doses increasing from 0.5 to 3.0 kGy. Especially under 3.0 kGy, the Verdet constant of BDF is 23.84% larger than that of SMF, and is 44.96% larger than that of SMF without irradiation treatment at 980 nm. After irradiation treatment, various defect structures are formed and valence states of bismuth ions transform to each other, which eventually contributes to the change of magneto-optical properties. These findings provide not only a candidate for the application of current sensor, but also a way to control valence states.
Funding
National Natural Science Foundation of China (61520106014, 61975113, 61635006, 61705126, 61935002).
References
1. G. M. Müller, W. Quan, M. Lenner, L. Yang, A. Frank, and K. Bohnert, “Fiber-optic current sensor with self-compensation of source wavelength changes,” Opt. Lett. 41(12), 2867 (2016). [CrossRef]
2. S. J. Petricevic and P. M. Mihailovic, “Compensation of Verdet Constant Temperature Dependence by Crystal Core Temperature Measurement,” Sensors 16(10), 1627 (2016). [CrossRef]
3. F. Suzuki, F. Sato, H. Oshita, S. Yao, Y. Nakatsuka, and K. Tanaka, “Large Faraday effect of borate glasses with high Tb3+ content prepared by containerless processing,” Opt. Mater. 76, 174–177 (2018). [CrossRef]
4. D. Huang, S. Srinivasan, and J. E. Bowers, “Compact Tb doped fiber optic current sensor with high sensitivity,” Opt. Express 23(23), 29993–29999 (2015). [CrossRef]
5. H. Hayashi, S. Iwasa, N. J. Vasa, T. Yoshitake, K. Ueda, S. Yokoyama, S. Higuchi, H. Takeshita, and M. Nakahara, “Fabrication of Bi-doped YIG optical thin film for electric current sensor by pulsed laser deposition,” Appl. Surf. Sci. 197-198, 463–466 (2002). [CrossRef]
6. Q. Chen, Q. Ma, H. Wang, and Q. Chen, “Structural and properties of heavy metal oxide Faraday glass for optical current transducer,” J. Non-Cryst. Solids 429, 13–19 (2015). [CrossRef]
7. Q. Jianrong and H. Kazuyuki, “Large Faraday effect in Bi2O3-based glasses,” Jpn. J. Appl. Phys. 35(12B), L1677 (1996).
8. M. Elisa, R. Iordanescu, C. Vasiliu, B. A. Sava, L. Boroica, M. Valeanu, V. Kuncser, A. C. Galca, A. Volceanov, M. Eftimie, A. Melinescu, and A. Beldiceanu, “Magnetic and magneto-optical properties of Bi and Pb-containing aluminophosphate glass,” J. Non-Cryst. Solids 465, 55–58 (2017). [CrossRef]
9. B. A. Sava, L. Boroica, M. Elisa, O. Shikimaka, D. Grabco, M. Popa, Z. Barbos, R. Iordanescu, A. M. Niculescu, V. Kuncser, A. C. Galca, M. Eftimie, and R. C. C. Monteiro, “Bismuth and lead oxides codoped boron phosphate glasses for Faraday rotators,” Ceram. Int. 44(6), 6016–6025 (2018). [CrossRef]
10. N. Peng, Y. Huang, S. B. Wang, T. Wen, W. Liu, Q. Zuo, and L. Wang, “Fiber Optic Current Sensor Based on Special Spun Highly Birefringent Fiber,” IEEE Photonics Technol. Lett. 25(17), 1668–1671 (2013). [CrossRef]
11. L. Sun, S. Jiang, J. D. Zuegel, and J. R. Marciante, “All-fiber optical isolator based on Faraday rotation in highly terbium-doped fiber,” Opt. Lett. 35(5), 706–708 (2010). [CrossRef]
12. Y. Huang, H. Chen, W. Dong, F. Pang, J. Wen, Z. Chen, and T. Wang, “Fabrication of europium-doped silica optical fiber with high Verdet constant,” Opt. Express 24(16), 18709–18717 (2016). [CrossRef]
13. Y. Kim, S. Ju, S. Jeong, and M. J. Jang, “Magneto-optic characteristics of gamma-ray irradiated Cu-doped optical fiber,” in OECC/PSC (IEEE, 2013), pp. 1–2
14. Y. Kim, S. Ju, S. Jeong, M. J. Jang, J. Y. Kim, N. H. Lee, H. K. Jung, and W. T. Han, “Influence of gamma-ray irradiation on Faraday effect of Cu-doped germano-silicate optical fiber,” Nucl. Instrum. Methods Phys. Res., Sect. B 344, 39–43 (2015). [CrossRef]
15. J. Wen, W. Liu, Y. Dong, Y. Luo, G. Peng, N. Chen, F. Pang, Z. Chen, and T. Wang, “Radiation-induced photoluminescence enhancement of Bi/Al-codoped silica optical fibers via atomic layer deposition,” Opt. Express 23(22), 29004–29013 (2015). [CrossRef]
16. J. Wen, J. Wang, Y. Dong, N. Chen, Y. Luo, G. Peng, F. Pang, Z. Chen, and T. Wang, “Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method,” Appl. Surf. Sci. 349, 287–291 (2015). [CrossRef]
17. C. B. Pedroso, E. Munin, A. Balbin Villaverde, N. Aranha, V. C. Solano Reynoso, and L. C. Barbosa, “Magneto-optical rotation of heavy-metal oxide glasses,” J. Non-Cryst. Solids 231(1-2), 134–142 (1998). [CrossRef]
18. Y. Ruan, R. A. Jarvis, A. V. Rode, S. Madden, and B. Luther-Davies, “Wavelength dispersion of Verdet constants in chalcogenide glasses for magneto-optical waveguide devices,” Opt. Commun. 252(1-3), 39–45 (2005). [CrossRef]
19. J. L. Cruz, M. V. Andres, and M. A. Hernandez, “Faraday effect in standard optical fibers: dispersion of the effective Verdet constant,” Appl. Opt. 35(6), 922–927 (1996). [CrossRef]
20. Y. Xu, H. Guo, X. Xiao, P. Wang, X. Cui, M. Lu, C. Lin, S. Dai, and B. Peng, “High Verdet constants and diamagnetic responses of GeS2-In2S3-PbI2 chalcogenide glasses for integrated optics applications,” Opt. Express 25(17), 20410–20420 (2017). [CrossRef]
21. J. Wen, W. Liu, Y. Huang, Y. Liu, Y. Luo, G. Peng, F. Pang, Z. Chen, and T. Wang, “Spun-Related Effects on Optical Properties of Spun Silica Optical Fibers,” J. Lightwave Technol. 33(12), 2674–2678 (2015). [CrossRef]
22. Y. Huang, L. Chen, Q. Guo, F. Pang, J. Wen, Y. Shang, and T. Wang, “The measurement system of birefringence and Verdet constant of optical fiber,” Proc. SPIE 9046, 904615 (2013). [CrossRef]
23. J. Wen, W. Wang, Q. Guo, Y. Huang, Y. Dong, F. Pang, Z. Chen, Y. Liu, and T. Wang, “Gamma-ray Radiation on Magneto-optical Property of Pb-doped Silica Fiber,” J. Inorg. Mater. 33(4), 416–420 (2018). [CrossRef]
24. J. Wen, T. Wang, F. Pang, X. Zeng, Z. Chen, and G. Peng, “Photoluminescence Characteristics of Bi(m+)-Doped Silica Optical Fiber: Structural Model and Theoretical Analysis,” Jpn. J. Appl. Phys. 52(12R), 122501 (2013). [CrossRef]
25. X. Meng, J. Qiu, M. Peng, D. Chen, Q. Zhao, X. Jiang, and C. Zhu, “Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses,” Opt. Express 13(5), 1635–1642 (2005). [CrossRef]
26. X. Meng, J. Qiu, M. Peng, D. Chen, Q. Zhao, X. Jiang, and C. Zhu, “Near infrared broadband emission of bismuth-doped aluminophosphate glass,” Opt. Express 13(5), 1628–1634 (2005). [CrossRef]
27. J. Zheng, M. Peng, F. Kang, R. Cao, Z. Ma, G. Dong, J. Qiu, and S. Xu, “Broadband NIR luminescence from a new bismuth doped Ba2B5O9Cl crystal: evidence for the Bi0 model,” Opt. Express 20(20), 22569–22578 (2012). [CrossRef]
28. S. Girard, Y. Ouerdane, G. Origlio, C. Marcandella, A. Boukenter, N. Richard, J. Baggio, P. Paillet, M. Cannas, J. Bisutti, J. P. Meunier, and R. Boscaino, “Radiation Effects on Silica-Based Preforms and Optical Fibers-I: Experimental Study With Canonical Samples,” IEEE Trans. Nucl. Sci. 55(6), 3473–3482 (2008). [CrossRef]
29. D. L. Griscom, “γ-ray-induced optical attenuation in Ge-doped-silica fiber image guides,” J. Appl. Phys. 78(11), 6696–6704 (1995). [CrossRef]
30. J. Wen, G. Peng, W. Luo, Z. Xiao, Z. Chen, and T. Wang, “Gamma irradiation effect on Rayleigh scattering in low water peak single-mode optical fibers,” Opt. Express 19(23), 23271–23278 (2011). [CrossRef]
31. J. Wen, W. Luo, Z. Xiao, T. Wang, Z. Chen, and X. Zeng, “Formation and conversion of defect centers in low water peak single mode optical fiber induced by gamma rays irradiation,” J. Appl. Phys. 107(4), 044904 (2010). [CrossRef]
32. Q. Chen, Y. Wang, and H. Wang, “Synthesis and properties of nanocrystal BiPO4 in diamagnetic PbO-Bi2O3-B2O3 glass,” J. Non-Cryst. Solids 481, 85–93 (2018). [CrossRef]
33. L. Liang, M. Gu, Y. Duan, X. Ma, F. Liu, X. Wu, L. Qiu, M. Chen, J. Liao, D. Shen, X. Zhang, B. Gong, X. Xue, W. Xu, and J. Wang, “Study on irradiation damage of Bi-doped PbWO4 crystal,” High- Energy Phys. Nucl. Phys. 27(6), 526–531 (2003).
34. M. Peng and L. Wondraczek, “Bi2+-doped strontium borates for white-light-emitting diodes,” Opt. Lett. 34(19), 2885–2887 (2009). [CrossRef]
35. S. Firstov, S. Alyshev, M. Melkumov, K. Riumkin, A. Shubin, and E. Dianov, “Bismuth-doped optical fibers and fiber lasers for a spectral region of 1600-1800nm,” Opt. Lett. 39(24), 6927–6930 (2014). [CrossRef]
36. V. O. Sokolov, V. G. Plotnichenko, V. V. Koltashev, and E. M. Dianov, “Centres of broadband near-IR luminescence in bismuth-doped glasses,” J. Appl. Phys. 42(9), 095410 (2009). [CrossRef]
37. Y. Fujimoto and M. Nakatsuka, “Infrared Luminescence from Bismuth-Doped Silica Glass,” Jpn. J. Appl. Phys. 40(Part 2, No. 3B), L279–L281 (2001). [CrossRef]
38. J. Zheng, M. Peng, F. Kang, R. Cao, Z. Ma, G. Dong, J. Qiu, and S. Xu, “Broadband NIR luminescence from a new bismuth doped Ba2B5O9Cl crystal: evidence for the Bi0 model,” Opt. Express 20(20), 22569–22578 (2012). [CrossRef]
