Post on 23-Feb-2016
description
«Radiation-induced processes in silica core high-OH optical fibers under gamma-irradiation of 60Co»
Baydjanov M.
Turin Polytechnic University in Tashkent www.polito.uzInstitute of Nuclear Physics, Uzbekistan www.inp.uz
2
Application of silica optical fibers
Telecommunication Sensors Dosimeters Medicine
Radiation-resistant optical fibers
DESY – beam loss monitoring Nuclear Reactors – transfer information in IR-region of spectrum LHC CERN – detection of high-energy charged particles UV-irradiation in medicine Nuclear Power Plant
In the future
ITER – plasma diagnostics (400-700 nm) Space technologies
Expansion of optical fiber application fields is continuing
Polymicro Technologies LLC
3
coreSiO2
Optical fiber
Type of core diameter, μm
Type of clad diameter, μm
Protective buffer
OH-group content, ppm
FVP300 SiO2 , 300 (F)SiO2 , 330 Polyimide 1000FIP300 SiO2 , 300 (F)SiO2 , 330 Polyimide <1
FSHA600 SiO2 , 600 Polymer , 660 Acrylate 1000JTFLH600 SiO2 , 600 Polymer , 660 Tefzel <1
Optical fiber samples
CCDR =1.1(Clad to core ratio)
Effective range of high-OH fibers is 400 – 500 nm
clad(F) SiO2
Buffer
cladpolymer
4
Why OH-groups?
OH-groups are formed during adding hydrogen gas during optical fiber drawing.Accompanied with two main processes: suppressing ruptured Si-O-Si bonds during fiber
drawing reducing radiation-induced defects
OH-groups are necessary to increase a radiation resistance
≡Si–O–Si ≡ → Si• + •O–Si → ≡Si–H + H–O–Si≡
PURE SILICA FIBERS with High-OH group content
≡Si• – electronic E′-center - absorption band 215 nm
•O–Si≡ – Non-bridging oxygen hole center (NBOHC) - absorption band 260, 620 nm
≡Si–O–H •O–Si≡ – NBOHC-H - absorption band 600 nm
MPNP’09
www.polymicro.com
5
What happens to optical parameters of fibers under the influence of ionizing radiation?
Radiation-induced absorption (induced losses) of light caused by color centers
Radiation-induced light emission Cherenkov’s effect – high-energy charged particles Luminescence of color centers
Reabsorption of induced emission
γ-rays γ-rays
1 2
3 3
4
5 6
7
Fig.1. Experimental setup for in-situ measurements of radiation induced losses and light emission under γ-irradiation of 60Co (1.25 MeV): 1) Probing lamp; 2) Lenses; 3) connectors; 4) Transporting part of fiber 5) EPP2000C Spectrometer; 6) PC; 7) Irradiated part of fiber coiled into a ring with diameter 4.5 cm.
6
7
Radiation induced losses of transmission
In-situ measurement of losses
Stable losses Unstable losses
Stable color centers Transient color centersUnstable color centers
- in-situ losses
- stable losses - unstable losses
Fig. 2. High-OH fiber FVP300: Relaxation kinetics after γ-irradiation.
8
00 02 05 08 11 14 17 200
0.5
1
1.5
2
2.5 450nmP=360R/s
92kRad 1Mrad4.7MRad 8MRad84MRad
t, min
A(λ
), dB
/m
00 02 05 08 11 14 17 200.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2 P=360R/s, D=84MRad
610nm 500nm450nm 400nm
t, min
A(λ
), re
lativ
e.un
.
Unstable losses are caused by unstable color centers that are created under irradiation and annealed within 10 min.
Stable losses are caused by stable color centers that are created under irradiation and living longer than 10 min.
9
0
0.5
1
1.5
2
2.5
3
3.5
4
300 400 500 600 700 800λ, нм
A(λ
), дБ
/м
1
2
34
а)
0
1
2
3
4
5
6
7
8
500 550 600 650 700 750 800 850λ, нм
A(λ
), дБ
/м
1
2 3 4
б)
Fig. 3. γ-induced in-situ losses:a) FVP300 at dose rate 6R/s (1) 8 10∙ 6; (3) 3,5 10∙ 7 Rad; at dose rate 360 R/s (2) 8 10∙ 6; (4) 3,5 10∙ 7.b) FIP300 at dose rate 6 R/s (1) 3,5 10∙ 6; (2) 8 10∙ 6 Rad; at dose rate 360 R/s (3) 3,5 10∙ 6; (4) 8 10∙ 6
Rad.
The magnitude of in-situ losses depends not-only on radiation dose but also dose rate
High-OH FVP300
Low-OH FIP300
Fig. 4. (1) 3,3∙103; (2) 2∙104; (3) 4∙105; (4) 3,5∙106; (5) 107; (6) 6∙107 Rad.
Fig. 5. (1) 1,2∙105; (2) 3,6∙105; (3) 5∙105 Rad
10
400 450 500 550 600 650 700 750 800 8500
0.51
1.52
2.53
3.54
4.55
λ, nm
A(λ
), dB
/m
1
23
Low-OH JT-FLH600
400 450 500 550 600 650 700 750 800 8500123456789
10
λ, nm
A(λ
), dB
/m
1
65
43
2
Low-OH FIP300
300 350 400 450 500 550 600 650 700 750 800 8500
0.51
1.52
2.53
3.54
4.55
λ, nm
A(λ
), dB
/m
12
34
56
High-OH FVP300
(1) 1.7 ∙105; (2) 1.5 ∙106; (3) 4.8 ∙106; (4) 8 ∙106; (5) 3.4 ∙107; (6) 8.45 ∙107 Rad
300 350 400 450 500 550 600 650 700 750 800 8500.0
0.2
0.4
0.6
0.8
1.0
λ, nm
A(λ
), dB
/m1 2
3
4
High-OH FSHA600
In-situ losses at dose rate 6 R/s
(1) 3.6 ∙103; (2) 104; (3) 4 ∙104; (4) 4.5 ∙105
11
Optical fibers with pure silica core and F-silica clad and high-OH group content shows better radiation resistance and that optical fibers with same core and polymer clad.
But the cost of silica/polymer fibers are low and diameter is higher .
If the maximum annual dose is not more that 108 Rad and temperature is under 100°C in addition very long length of fiber is required then it is convenient to use silica/polymer fibers.
Optical fiber with buffer (coating) Tefzel is not radiation resistant!
0
0.1
0.2
350 400 450 500 550 600 650λ, нм
A(λ
), дБ
/м
D=7.8кРад
1
2
3
D=52.4кРад
0
0.1
0.2
0.3
0.4
350 400 450 500 550 600 650λ, нм
A(λ
), дБ
/м
123
1
D=0.75МРад
0
0.5
1
1.5
350 400 450 500 550 600 650λ, нм
A(λ
), дБ
/м
12
31
30
0.5
1
1.5
2
2.5
350 400 450 500 550 600 650λ, нм
A(λ
), дБ
/м
D=1.45МРад
123
Fig. 6. In-situ (1), stable (2) and unstable (3) losses spectra in FSHA600, measured at 10 R/s. The length of irradiated part is L=5 m.
12
Comparing stable and unstable losses
Fig 7. Dose dependency of induced losses at 610 nm in high-OH fibers.
≡ Si – O – Si ≡ → ≡ Si – O• + •Si ≡ (1)
≡ Si – O – H H – O – Si ≡ → ≡ Si – O• H – O – Si ≡ + H+ (2)
≡ Si – H → ≡ Si• H0 or HCl (3)
≡ Si – O – H → ≡ Si – O• + HCl (4)
≡ Si – Cl → ≡ Si• HCl (5)
13
A(λ)
, dB
/m
Dose, Rad (log. scale)
0
2
4
105 106 107 108
FSHA600
0
2
4
6
8
Dose, Rad (log. scale)
105 106 107 108
A(λ)
, dB
/m
2?108
FVP300
Fig. 8. Unstable losses spectra for high-OH FVP300 at the doses: 1) 9,2·104; 2) 106; 3) 4,7·106; 4) 7,9·106; 5) 3,4·107; 6) 5,9·107; 7) 8,4·107; 8) 108; 9) 2·108 Rad (P=360 R/s).
Fig. 9. Unstable losses spectra for low- OH FIP300 at the doses:1) 2,3·105; 2) 106; 3) 1,7·106; 4) 2·106; 5) 3,5·106; 6) 8·106; 7) 3,4·107; 8) 6·107; 9) 1,5·108; 10) 2·108 Rad (Р=360 R/s)
≡ Si – O – Si ≡ → ≡ Si – O- + •Si ≡ (6)≡ Si – H → ≡ Si• + H+ (7)
≡ Si – O – H → ≡ Si – O• + H + (8)≡ Si – Cl → ≡ Si• + Cl (9)
00.5
11.5
22.5
33.5
44.5
5
500 550 600 650 700 750 800 850λ, nm
A(λ
), дБ
/м
1
2
345
6 7-10
00.20.40.60.8
11.21.41.61.8
2
300 350 400 450 500 550 600 650 700 750λ, nm
A(λ
), дБ
/м
12
3
45-8
14
Increasing of unstable losses intensity with dose
0
0.2
0.4
0.6
0.8
1
1.2
1.4A
(λ),
дБ/м
400 нм450 нм500 нм
105 106 107 108
Dose, Rad (Log. scale)
FSHA600
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
A(λ
), дБ
/м
400нм450нм500нм610нм
104 105 106 107 108 109
Dose, Rad (Log. scale)
FVP300
Fig. 10. Dose dependency of unstable losses in high-OH fibers.
0
0.5
1
1.5
2
2.5
3
3.5
4
A(λ
), дБ
/м
650 нм670 нм700 нм650670700
Dose, Rad (Log. scale)105 106 107 108 109
FIP300
Fig. 11. Dose dependency of unstable losses in low-OH fibers
15
16
If the diameter of the core of fiber is larger then the number of unstable color centers will be smaller, so fiber becomes more resistant to radiation.
Linear dependence of unstable losses and saturation effect can be used for dosimetry purposes.
17
If unstable losses are caused by unstable color centers then where is its maximum located?
What is the nature of this center?
How the number of this center can be reduced?
Fig. 12. UV-induced losses spectra in high-OH fiber FVP300: (1) right after irradiation (2) 10 min after irradiation;
Fig. 13. Difference of (1) – (2) from Fig. 12.
012345678
200 220 240 260 280 300λ, нм
A(λ
), дБ
/м
1
2
0
0.2
0.4
0.6
0.8
1
1.2
200 220 240 260 280 300λ, нм
A(λ
), дБ
/м
1 - 2
Fig. 14. UV-induced losses spectra after excitation pulses n=20 – 100.
012345678
200 220 240 260 280 300λ, нм
A(λ
), дБ
/м
20
3040
50 6070
8090
100
18
UV-induced losses in high –OH fuber
00.20.40.60.8
11.21.41.6
0 100 200 300 400Dose rate, R/s
A(λ
), dB
/m
1
2
3
00.20.40.60.8
11.21.4
0 100 200 300 400Dose rate, R/s
A(λ
), dB
/m
1
2
3
00.20.40.6
0.81
1.21.4
0 100 200 300 400Dose rate, R/s
A(λ
), dB
/m
1
2
3
0
0.5
1
1.5
2
2.5
3
0 100 200 300 400Dose rate, R/s
A(λ
), dB
/m
1
2
00.20.40.60.8
11.21.4
0 100 200 300 400Dose rate, R/s
A(λ
), dB
/m
1
2
Fig. 15. Dose rate dependency of induced losses in high-OH fiber FVP300 in wavelength range 450 nm: 1) in-situ; 2) unstable.
4,7·106 Рад 3,4·107 Rad
4,7·106 Rad 8·106 Rad 3,4·107 Rad
Fig. 16. Dose rate dependency of unstable losses in high-OH fiber FVP300 in different wavelength ranges: 1) 400 nm; 2) 450 nm; 3) 600 nm.
Linear dependence can be used as a parameter to control radiation dose rate19
0
0.5
1
1.5
2
0 100 200 300 400Dose rate, R/s
A(λ)
, dB/
m 1
2
4,7·106 Rad 8·106 Rad
20
γ-Radiation Induced Light Emission
Cherenkov’s emission Radioluminescence
Transporting part - L
Spectrometer
Irradiated part - lg
Influence of reabsorption process on radiation-induced emission in fibers
Intensity of Cherenkov’s emission
N
n
lnlALAR II g
10
1,01.0 1010 0
IR(λ) – Intensity of Cherenkov’s emission exposed to reabsorption within transporting (L) and irradiated (lg) lengths of optical fiber
lg L
(1)
301~
I
21
350 450 550 650 750 8500
0.5
1
1.5
2
λ, nm
I R(λ
), ar
b. u
n.
a)1
2
34
Fig. 17. Possible spectra of Cherenkov’s emission plotted by formula (1) at different given values for lg and L:
a) 1 – Real spectrum of Cherenkov’s emission plotted by formula I0(λ)=k/λ3;2 – lg=4 m and L=22 m. A(λ) for D=106 Rad, P=70 R/s (МТ-22С-accelerator));3 – lg=3 m и L=6 m, A(λ) при D=1,5 10∙ 6 Рад, P=360 Р/с;4 – при D=1,5 10∙ 6 Рад.
b) A(λ) for D=106 Rad; P=70 R/s (МТ-22С-accelerator), 1 – построенный по I0(λ)=k/λ3;2 – L=5 m;3 – L=22 m;4 – L=50 m.
350 450 550 650 750 8500
0.5
1
1.5
2
λ, nm
I R(λ
), ar
b. u
n.
b)1
2
34
22
23
Dependence of the length of transporting fiber on reabsorption
200 300 400 500 600 700 8000
0.02
0.04
0.06
0.08
Wavelength, nm
Inte
nsity
, arb
. uni
ts
Zoom a)5 6 7
8910
1112
13
1415
200 300 400 500 600 700 8000
0.2
0.4
0.6
0.8
1
Wavelength, nm
Inte
nsity
, arb
. uni
ts
a)0
1
2
3
4
5
0
1
2
34
200 300 400 500 600 700 8000
0.2
0.4
0.6
0.8
1
Wavelength, nm
Inte
nsity
, arb
. uni
ts
b)
5
200 300 400 500 600 700 8000
0.02
0.04
0.06
0.08
Wavelength, nmIn
tens
ity, a
rb. u
nits
5
6
7
8 9
1011
1213
1415
Zoom b)
Fig. 2. Theoretical Cherenkov’s emission spectra (curve (0)) and plotted by eq. 2) for different length of fiber samples: a) FVP; b) J-LowSol; c) J-UltraSol. Numbered curves correspond to the length of fibers as follows: (1) – 1 m; (2) – 2 m; (3) – 5 m; (4) – 10 m; (5) – 20 m; (6) – 50 m; (7) – 75 m; (8) – 100 m; (9) – 150 m; (10) – 200 m; (11) – 250 m; (12) – 300 m; (13) – 400 m; (14) – 500 m; (15) – 103 m.
24
200 300 400 500 600 700 8000
0.2
0.4
0.6
0.8
1
Wavelength, nm
Inte
nsity
, arb
. uni
ts
c)0 12
3
4
56
200 300 400 500 600 700 8000
0.02
0.04
0.06
0.08
Wavelength, nm
Inte
nsity
, arb
. uni
ts
Zoom c)5
6
7 8
91011
1213
1415
From 1 to 20 m J-UltraSol sample has the best performance, 2nd FVP and 3rd is J-LowSol.
At the length of 20 m for J-UltraSol the intensity magnitude is still highest while for FVP and J-LowSol it is comparably equal.
At 20 < L < 75 m J-UltraSol, J-LowSol and FVP correspondingly in order of highest intensity to lowest.
100 < L < 250 m – J-UltraSol, FVP, J-LowSol.
250 < L < 1000 m – FVP, J-UltraSol, J-LowSol.
25
Reabsorption takes place in irradiated and transporting parts of optical fibers.
Reabsorption depends on the lengths of irradiated part, transporting part and dose of irradiation.
Reabsorption changes the shape of real spectrum – deformation of spectrum.
Is it possible to restore the real shape of the spectra?
Yes, if we measure in-situ losses simultaneously with radiation-induced emission spectrum!
Method of restoring the true emission spectra
26
l
I0
Irradiated part of fiber
AAlNAAlAAL
AAlLA
Rirr
trINI000
0
0
1.011.01.0
1.01.0
101010
11010
Intensity of true emission with taking into account reabsorption within irradiated and transporting parts of optical fiber.
Details in Jap. J. Appl. Phys. 2008 (47) 1 301-302.
Fig. 18. γ-induced light emission spectra of high-OH fibers: a) measured; b) and c) after calculations.1 – 7,3∙104; 2 – 1,4∙106; 3 – 5∙106; 4 – 8∙106; 5 – 3,45∙107; 6 – 6∙107 Рад, P=360Р/с.
27
c)
FVP300true
FVP300false
Fig. 20. Real spectrum (1), Cherenkov’s emission spectrum (1/λ3) (2) and their difference (3).
Fig. 19. Difference of spectra (6) and (1) from Fig. 18 b) and c).
28
λ, nm 350 450 550 650 750 850
0,5
1
1,5
λ, nm 350 450 550 650 750 850
0,5
1
1,5
Inte
nsity
arb
. uni
ts
12
3
44-1
350 450 550 650 750 850λ, nm
0
1
1,5
1
3
20,5
б)
350 450 550 650 750 850λ, nm
0
1
1,5
3-1
0,5
Inte
nsity
arb
. uni
ts
Fig. 21. γ-induced light emission of high-OH FVP300:а) at dose rates 10 (1), 40 (2), 70 (3) R/s;b) Different of curves 3-1. Irradiated by bremmhstrahlung γ-radiation of MT-22C accelerator.
Fig. 21. γ-induced light emission of high-OH FVP300:а) at dose rates 6 (1), 65 (2), 160 (3), 360 R/s (4);b) Different of curves 4-1. Irradiated by 60Со source.
29
a)
a) b)
b)
30
Fig. 23. Dose rate dependency of emission intensity at the wavelength 450 and 650 nm.
0
2
4
6
8
10
12
0 100 200 300 400P, R/s
Inte
nsity
, arb
.un.
450 nm
650 nm
Increasing dose rate brings to the increase of the number secondary electrons responsible for Cherenkov’s emission therefore its intensity increases linearly.
This linear dependence of radiation induced light emission can be used to control dose rates of radiation sources or beam loss monitoring.
31
In-situ measurements can give us full information about optical properties of radiation resistant fibers.
Reabsorption causes deformation of radiation-induced emission spectra therefore it must be taken into account.
Linear dependencies of unstable losses, light emission on dose or dose rate can be used in development of fiber based detectors of radiation.
The method presented here probably can be used in beam loss monitoring with silica fibers.
Fig. 24. Dose dependencies of absorption band at (1) 610 nm, luminescence bands (2) 450 and (3) 650 nm. (norm. un.)
It was supposed that 610 nm absorption band is formed by the sum of absorption bands of two types of NBOHC: 600 nm (Si–O• H–O–Si) and 630 nm Si–O•
Difference in dose dependencies of absorption band 610 nm and luminescence bands 450 and 650 nm shows that : some part of NBOHC are making non-radiative relaxation. different centers other than NBOHC are also responsible for formation of 610 nm
absorption band.
32
Influence of preliminary neutron irradiation on color centers creation under gamma-irradiation
0
20
40
60
80
100
120
140
200 250 300 350 400λ, нм
A(λ
), дБ
/м
3-1
2-1
4-1
0
20
40
60
80
100
120
200 250 300 350λ, нм
A(λ
), дБ
/м
1
7
6
54
3
2
0
1
2
3
4
5
6
7
350 450 550 650 750 850λ, нм
A(λ
), дБ
/м
1- 92кРад2- 1МРад3- 4,7МРад4- 8МРад5- 34МРад6- 34,5МРад7- 84МРад8- 0.1ГРад9- 2ГРад
Fig. 25. γ-induced losses spectra of high-OH FVP300 fiber preliminary unirradiated by neutrons at the doses:103 (1), 5·103 (2), 104 (3), 5·104 (4), 5·106 (5), 5·107 (6) and 108 Rad (7)
а) UV-range.б) differences of spectra;в) VIS-range
1234
5
67
8
9
33
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
450 500 550 600 650 700λ, нм
A(λ
), дБ
/м 7
6
5
4
8Fig. 26. γ-induced losses spectra of high-OH FVP300 fiber preliminary irradiated by neutrons fluence 1012 n·cm-2
a) UV-range;b) VIS-range.Doses: 105 (1), 5·105 (2), 106 (3, 4), 5·106 (5), 107 (6), 5·107 (7), 108 Rad (8).
0
20
40
60
80
100
120
140
200 250 300 350 400λ, нм
A(λ
), дБ
/м
4-1
3-1
2-10
10
20
30
40
50
60
70
200 250 300 350
A(λ
), дБ
/м
3
2
1
4
56
34
0
12
3
45
6
78
9
400 450 500 550 600 650 700λ, нм
A(λ
), дБ
/м
1
7
6
5
43
2
0
1
2
3
4
5
6
7
8
4 5 6 7 8lgD, Рад
A(λ
), дБ
/м
1
23
Fig. 27. γ-induced losses spectra of high-OH FVP300 fiber preliminary irradiated by neutrons fluence 1014 n·cm-2
Doses 105 (2), 5.105 (3), 106 (4), 9.106 (5), 1,5.107 (6) and 6,5.107 Rad (7)
Fig. 28. Kinetics of change of the value of A(λ) at 610 nm in(1) preliminary unirradiated.(2) preliminary irradiated by 1012 n·cm-2.(3) 1014 n·cm-2.
35
O Si H
γ
γ e-
e- e- γ
e+
e+
36
Effect of high temperature heating on transmission recovery of irradiated high-OH fibers
0
1
2
3
4
5
6
350 400 450 500 550 600 650 700λ, нм
Инд
уцир
ован
ные
поте
ри, д
Б/м
4
2
5
3
16
7
7
6
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
350 400 450 500 550 600 650 700λ, нм
Инд
уцир
ован
ные
поте
ри, д
Б/м
8
9
8
9
10,11,12
13
13
Fig. 29. Spectra of γ-induced losses before Aγ(λ) (1) and after heating ΔAi(λ) after the following temperatures:1000С (2);1500С (3);2000С (4);2500С (5);3000С (6);3500С (7);(8) 4000С;(9) 4500С;(10) 5000С;(11) 5500С;(12) 6000С;(13) after cooling to room temperature.
37
-0.3-0.2-0.1
00.10.20.3
0.40.50.6
300 350 400 450 500 550 600 650 700λ , nm
ΔA(λ
), дБ
/м1
12 2
-0.4
-0.2
0
0.2
0.4
0.6
0.8
300 350 400 450 500 550 600 650 700λ , nm
ΔA(λ
), дБ
/м
33
4
4
-0.5
0
0.5
1
1.5
2
2.5
300 350 400 450 500 550 600 650 700λ , nm
ΔA(λ
), дБ
/м 5
5
5
6
6
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
300 350 400 450 500 550 600 650 700λ , nm
ΔA(λ
), дБ
/м 7
8
8
9 9
-0.2
-0.1
0
0.1
0.2
0.3
300 350 400 450 500 550 600 650 700λ , nm
ΔA(λ
), дБ
/м
10 1011
Fig. 30. Difference of curves of Fig 29.:1) 1-2; 2) 2-3; 3) 3-4; 4) 4-5; 5) 5-6; 7) 7-8; 8) 8-9; 9) 9-10; 10) 10-11; 11) 11-12; 6) 6-7; 12) 12-13;
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300 350 400 450 500 550 600t , C
K(λ
), от
н.ед
.
380nm 425nm
600nm 650nm0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300 350 400 450 500 550 600t , C
K(λ
), от
н.ед
.
360nm 450nm
550nm 400nm
Fig. 31. Temperature dependence of K(λ)=Ai(λ)/Aγ(λ)
38
39