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Radiation Effects on Optical Fibers and Fiber-based Sensors
Recent Advances and Future Challenges
Sylvain Girard
Phone: +33 (0) 477 915 812
CERN Seminar, Geneva, Sept. 27th, 20161
Outline
Review paper: S. Girard, J. Kuhnhenn, A. Gusarov, B. Brichard, M. Van Uffelen, Y. Ouerdane, A. Boukenter, and C. Marcandella, “Radiation Effects on Silica-based Optical Fibers: Recent Advances and Future Challenges”, IEEE TNS, vol.60 (3) 2015 - 2036, 2013
• Introduction: Context of our work• Part 1: Basic mechanisms of radiation effects on optical fibers• Part 2: Recent Advances on radiation hardened optical fibers• Part 3: Recent Advances on radiation hardened fiber-based sensors• Part 4: Future Challenges
Introduction: Context of our work
Coating
Cladding
Core
Amorphous silica
Silica-based optical fibers (OFs) are made with pure or doped amorphous silica (a-SiO2) glass
Telecom-grade optical fibers : Single-mode or Multimode Polarization-maintaining optical fibers Rare-earth doped optical fibersMicrostructured optical fibers Hollow core optical fibers Plastic optical fibers
In this talk, we focus on silica-based optical fibers for whichthe light guiding is ensured by Total Internal Reflection (TIR)
Few modes optical fibers Polarising optical fibers IR-optical fibers (sapphire)
Silica-based optical fibers can be designed for light transmission from the ultraviolet to the IR part of spectrum (250 – 2µm)
0.1 0.2 0.7 0.8 0.9 11 2 3 5 100.3 0.4 0.50.6
12 10 8 6 4 2
10-2
100
102
104
106
108
1010
1012
Queue d'Urbach
Défauts (?)
Défauts induits par irradiation
Impureté OH
Diffusion (-4)
Att
én
uati
on
op
tiq
ue (
dB
/km
)
Défauts
Energie du photon (eV)
3
2.0 1.5 1.0 0.5 0.0
Impureté OH
Longueur d'onde (m)
Queue multiphonon
Diffusion
2
1310 nm
1550 nm
0.15
4
0.5
Wavelength (µm)O
pti
cal a
tte
nu
atio
n (
dB
/km
)
Photon Energy (eV)
Data links Diagnostics
• Laser• Plasma
Fiber lasers Fiber amplifiers Sensing
• Strain• Temperature• Dose• Gyroscopes
Since Fukushima event, OFS are more and more considered by nuclear industry
Various OFS technologies exist, exploiting the a-SiO2 structural and optical properties
Vulnerability and hardening studies of OF and fiber-based sensors (OFS) in severe environments
1. Electromagnetic immunity
2. High bandwidth/ multiplexing capability
3. Low attenuation
4. Low weight and volume
5. High temperature resistance
1 Gy=100 rad
Part 1: Basic Mechanisms of Radiation Effectson Optical Fibers
3 degradation mechanisms at macroscopic scale have been identified under irradiation
1. Radiation-Induced Attenuation (RIA)
2. Radiation-Induced Emission (RIE)
3. Compaction
CourtesyB. Brichard(SCK-CEN)
The relative contributions of these 3 mechanisms depend on the radiation environment, on
the targeted application and on the fiber properties
Radiation-induced mechanisms occurring at the microscopic scale in a-SiO2 have been identified…and are a bit complex
Optically-active point defects are induced by irradiations. Their properties are responsible for the degradation of OFs
Griscom D.L. SPIE vol. 541, 1985
Aggregates:
Colloids, Bubbles
UV Light
X Rays
g Rays
Fast
ElectronsNeutrons
Fast Ions
Electron-Hole
Pairs
Atomic
Displacement
I II III IV V
Recombination
Free Vacancies
And Interstitial
Free Carriers
Recombination
Light Emission
Transient Defects
Photolytic Defects
Radiolytic
Fragments
(Principally H°)
DIFFUSION-LIMITED
REACTIONS
CARRIER
TRAPPING DEFECT
FORMATION
EXCITED STATE
RELAXATION
RCOMBINATION
IRRADIATION PROMPT
OCCURRENCE
(Compton Electrons)
(Secondary
Electrons)
Trapping at
Radiolytic Defects
Trapping at
Preexisting Defects
Trapping at
Impurities
Trapping at
Knock-on damages
Dimerization
Self-trapping
Further Diffusion-
Limited Reactions
Stabilization by
diffusion of charge-
compensating Ions
Optical and energy properties of these point defects explain the complexity of the OF radiation-response
STH1
STH2
POR
NBOHC
E'
ODC
Each parameter affecting the stability, generation efficiency or optical properties of these point defects will affect the OF radiation response.
Too complex to be yet predictable!
L. Skuja; NATO Book Chapter, 2000
Griscom D.L. SPIE vol. 541, 1985
Numerous parameters, intrinsic or extrinsic, influence the OF radiation response
These parameters affect the RIA levels & kinetics that generally define the OF vulnerability
Fiber sensitivity strongly depends on the fiber composition: core dopants, process parameters are less impacting
No ideal composition exists, their relative RIA levels depend on the radiation environments, fiber profile of use…
Fiber sensitivity strongly depends on the fiber composition: cladding dopants, stœchiometry, impurities, …
• A slight change in composition strongly changes the nature, concentration and stability of induced defects
2 Telecom SMF same reference and different cladding compositions
0 500 1000 1500 2000 2500 3000 3500 40000
3
6
9
12
15
RIA
(d
B/k
m)
Time (s)
SM_GeP
SM_Ge
0.8 MeV neutrons
5x1013
n/cm²
1550nm
0 500 1000 1500 2000 2500 3000 3500 40000
3
6
9
12
15
RIA
(d
B/k
m)
Time (s)
SM_GeP
SM_Ge
0.8 MeV neutrons
5x1013
n/cm²
1550nm
Fiber vulnerability: RIA growth kinetic depends on the harsh environment: dose, dose rate, T, irradiation duration,…
Vulnerability strongly depends on the harsh environment associated with the application what means COTS Rad Hard Fibers?
Temperature parameter has been too poorly and badly studied (R+T instead R&T)
Fiber vulnerability: RIA levels and kinetics depends on the temperature of irradiation
S. Girard, et al., IEEE TNS, 60(6), pp. 4305 - 4313, 2013.
1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.010.0
0.5
1.0
1.5
2.0
2.5
RIA
(d
B/m
)
Time (s)
X-ray pulse
RIA
bleaching
Ge-doped optical fiber
1550nm, 51Gy
Fiber vulnerability: RIA decay kinetic after irradiation drive the fiber recovery between successive irradiations
Majority of defects is unstable at the temperature of experiments the RIA decreases with time after irradiation
The bleaching kinetics and efficiency depend on many parameters: wavelength and power levels of the injected signal, …
H. Henschel et al., IEEE TNS 49, 2002
Influence of injected light power
0.1µW
1µW
38µW
Part 2a: Recent Advances on radiation hardenedoptical fibers
CERN LHC: identification of a radiation hardened SMF @1310nm(steady state, 100 kGy dose level)
• F-doped fiber + ?• Very complex
radiation response• Strongly dependent
on irradiation conditions
T. Wijnands, et al., JLT 29, 3393-3400 (2011)T. Wijnands, et al., IEEE TNS. 55, 2216-2222 (2008)
ITER diagnostics: RIA mitigation techniques can be applied to reduce the fiber sensitivity for given application and radiation environment
For some applications, loading of the fiber with H2, (D2 or O2) can reduce the RIA
wavelengths: difficult to predict too!
Low OH silica without H2
RIA
[d
B/
m]
Low OH silica with H2
RIA
[d
B/
m] POSITIVE IMPACT
NEGATIVEIMPACT
Characterize, reduce the component vulnerability (EMP and radiations): electronics (CCD, transistor, memory,...), optics (fiber optics, glasses), CMOS image sensors (ISAE-CEA-LabHC)
2m thick outer wall to protect outside workers and adjacent buildings
X-rays14 MeV ng-rays
Monte Carlo Simulation of dose and dose rate levels
Electromagnetic Pulse
LMJ control command: All the equipments located inside the E.H. have to be radiation-tolerant to the LMJ mixed environment
Control-command links mainly operate at Telecom wavelengths, before and after theLMJ shots Evaluation of the vulnerability of COTS components Guidelines for the LMJ design engineers
LMJ control command: COTS fibers have been selected and systems adapted to the transient irradiation constraints
S. Girard et al., IEEE TNS 52, 1497, 2005
S. Girard et al., IEEE TNS 52, 2683, 2005
S. Girard et al., IEEE TNS 53,1756, 2006.
LMJ: Vulnerability of a large panel of optical fibers has to be characterized to the LMJ harsh environment: prototype fibers
Laser diagnostics: operate during the shot, mainly at 3.
Plasma diagnostics: operate during the shots, from 1 to 3.
Biggest challenge: time-resolved diagnostics (time resolution <1ns) in the ultraviolet part of the spectrum
RIA is larger for shorter times, shorter wavelengths No comparable studies in literature
R&D development in progressno commercial product has the required characteristics forthe diagnostics @ 3
Space: recent achievements on the radiation hardening of rare-earth based optical fibers and amplifiers: Ce-doping + H2 loading
HACC fibers• Hardening by
composition• Hardening by
structure
S. Girard et al., Opt. Lett. 39, 2541-2544 (2014) S. Girard et al., IEEE TNS 61(6), 3309, 2014
Radiation Hard Optical Fibers exist today for most of IR applications at MGy dose
More efforts are in progress to have a full product (cable, connectors,…) qualified for harsh environments
CHALLENGES: Fibers for UV operation for fusion/ fission New fiber generations (PCF, HACC, metal-coated,…) Fiber amplifiers and fiber-based lasers
Today, functionalization of OF is targeted in order that in addition to data transfer, fibers can beused to monitor environmental parameters
COTS Radiation tolerant or hardened optical fibers are now available for some applications/environments
Part 3: Recent Advances on radiation hardenedfiber-based sensors
DISCRETE SENSING(temperature, strain)
DISTRIBUTED SENSING(temperature, strain, liquidlevel, pressure,..)
PUNCTUAL, ONLINE, OFFLINE SENSING
The vulnerability and hardening studies of OFS technologies is under progress
• Fiber Bragg Gratings (strain, temperature, ….)
• Raman (T)• Brillouin (T, strain,…)• Rayleigh (T, strain, …)
• Dosimetry• RIA (active, distributed)• TL (passive)• RIL, OSL (active punctual)
Advantages:
– Small size (Ø~100µm), Light weight
– Resistance to electromagnetic interference
– No need of electrical power at the sensing point
– Quick response (<1s), Multiplexing
FBG Temperature & Strain Sensing in Nuclear Industry
2. Tuneable laser interrogation unit illuminates fibre and measures reflected Bragg wavelengths
1. Numerous sensors recorded on a single fibre, mm or km apart. Sensors can measure strain, pressure, temperature etc
3. Processing Unit converts wavelengths to measurands of interest, which are displayed real time or logged for future analysis
Fibre
Data
FBG Sensors
http://www.fbgs.com
Degradation of OF RIA
Influence on the FBG properties:– Amplitude: possible FBG erasing under
irradiation loss of OFSfunctionality
– Bragg Wavelength Shift: error on T measurements OFS performance degradation
Radiation effects on FBG properties
A. Morana et al., Opt Express, 23(7), 8663 (2015)
1MGy
10pm= 1°C error
What is the best FBG technology for MGy dose levels (nuclear industry)?
A. Gusarov et al., IEEE TNS, 60, 2037(2013)
Composition
Temperature
Nature of particles DoseDose rate
Irradiation conditions
Post-treatmentsFBGs
Laser types (UV, IR,…)
Pulse duration,frequency
Inscription conditions
Pre-treatments
Optical properties
Fiber optic
Parameters impacting the FBG response
We identified a procedure to develop RH FBGs for high T operation (up to 350°C)
LabHC-AREVA patent (Dec. 2013)
0104
3104
6104
9104
12104
-20
-15
-10
-5
0
5
10
-1.0
-0.8
-0.5
-0.3
0.0
0.3
0.5
Irrad.Irrad. Recovery
0
Ind
uced
Tem
peratu
re Variatio
n (°C
)
3MGy1.5MGy
Bra
gg
Wav
elen
gth
Sh
ift
(pm
)Time (s)
0104
3104
6104
9104
12104
15104
18104
-2
0
2
4
6
8
10
12
-0.2
0.0
0.2
0.4
0.7
0.9
1.1
1.3
RecoveryRecovery Irrad.Irrad.
0
Ind
uced
Tem
peratu
re Variatio
n (°C
)
3MGy1.5MGy
Bra
gg
Wav
elen
gth
Shif
t (p
m)
Time (s)
ROOM TEMPERATURE (~25°C) HIGH-T (~230°C)
A. Morana, et al. Opt. Letters 39 (18) 5313, 2014
These RH FBGs also present the best response to high-T (300°C) and high fast neutron fluence up to 3×1019n/cm² (collaboration with CEA DEN/DRT)
RH-FBGs are made with fs lasers following the patented procedure into RH-OF
HOBAN LabHC - AREVA –
FINT– iXBlue –SmartFibres
Development of hard optical fiber Bragg grating sensors
(2015 -2017)
DISCRETE SENSING(temperature, strain)
DISTRIBUTED SENSING(temperature, strain, liquidlevel, pressure,..)
PUNCTUAL, ONLINE, OFFLINE SENSING
The vulnerability and hardening studies of OFS technologies is under progress
• Fiber Bragg Gratings (strain, temperature, ….)
• Raman (T)• Brillouin (T, strain,…)• Rayleigh (T, strain, …)
• Dosimetry• RIA (active, distributed)• TL (passive)• RIL, OSL (active punctual)
e, DT ?
Acquisition system
Distributed sensing based on backscattered light into OFs
PhD thesis Xavier PhéronPhD thesis Serena RizzoloPhD thesis Chiara CangialosiPhD thesis Isabelle Planes
• Temperature and strain monitoring will be implemented in the envisioned French geological repository for high- and intermediate-level long-lived nuclear wastes.
ANDRA needs for radioactive waste storage
Investigations of Gamma radiation and hydrogen release effects on Ramanand Brillouin sensors to provide T, strain discrimination using a 2 fiber cable
• Radiations affect Brillouin sensors by different ways:
– RIA limits the possible distance range
– Radiation shifts the BFS direct error on the T or strain measurement
Brillouin-based distributed temperature measurements is possible at MGy dose levels
By using best optical fibers, it is possible to limit the error below 1-2°C at MGy dose over hundredths of meters
C. Cangialosi, PhD Thesis, 2016
• Radiations affect Raman sensors by different ways:
– RIA limits the possible distance range (x2 in the case of double-ended)
– Radiation can affect the S/AS ratio direct error on the T measurement due to DRIA
Raman-based distributed temperature (RDTS) measurements are not possible with single-ended (SE) commercial sensors
Hardening is not possible by components the architecture of the sensors must be adapted
C. Cangialosi, PhD Thesis, 2016
I. Toccafondo, PhD thesis, 2015I. Toccafondo, IEEE Photonics Technology Letters, 27 (20) 2182-2185, 2015
Solve DRIA issues, ×2 RIA issues
Raman-based distributed temperature (RDTS) measurements are possible with double-ended (DE) commercial sensors
This new SE-RDTS architecture limits both RIA and DRIA issues
A Hardening-by-System approach allows us to perform Raman measurements at high doses
Di Francesca et al., IEEE TNS, accepted, 2016.
AccidentalConditions
Temperature 100 °C
Humidity 100%
Pression 200 kPa
Radiation 450 kGy in 30 days
Operating Conditions
Temperature 10 - 60 °C
Humidity 0 - 95%
Pression 86 -106 kPa
Radiation 1 MGy in 40 years
SFP DEPTH 12
m Water at 100 °C and steam
Minimum Permitted Level ~ 6.5 m
NEED: Development of a distributed TEMPERATURE and WATER LEVEL sensor for STORAGE FUEL POOLS
Fuel Storage Racks ~ 4 m
Rayleigh-based OFS: Fukushima-Daichii accident: a break point in the nuclear safety rules
39
CHALLENGE: Ability to withstand to
ACCIDENTAL CONDITIONS
Very recent results demonstrated the potential of this technique for monitoring T, strain in nuclear facilities
OFDR reflectometry is a very promising technique with a high spatial resolution (100µm over 70m for LUNA OBR4600)
Limited knowledge about radiation effects on this technology (Alexey Faustov, PhD <100kGy TID)
Rayleigh scattering is not affected by irradiation, at least up to 10MGy
Only RIA limits the fiber sensing range
S. Rizzolo, et al., Optics Express, vol.23 (15), 18998 , 2015.
S. Rizzolo, et al., Optics Letters, 2015 ; S. Rizzolo et al., IEEE TNS, 2015.
AREVA – LabHC, 2015 pending patents
Water level is well detected with a F-doped OF with polyimide coating
S. Rizzolo, PhD Thesis, 2016
DISCRETE SENSING(temperature, strain)
DISTRIBUTED SENSING(temperature, strain, liquidlevel, pressure,..)
PUNCTUAL, ONLINE, OFFLINE SENSING
The vulnerability and hardening studies of OFS technologies is under progress
• Fiber Bragg Gratings (strain, temperature, ….)
• Raman (T)• Brillouin (T, strain,…)• Rayleigh (T, strain, …)
• Dosimetry• RIA (active, distributed)• TL (passive)• RIL, OSL (active punctual)
Thermoluminescence (TL) passive dosimetry with Ge-doped OFs
Possible applications: Medicine, High Energy FacilitiesPerspectives: OSL for online dose rate measurements?
M. Benabdesselam, et al., JNCS, 360, 9, 2013
M. Benabdesselam, et al., IEEE TNS, 60(6), 4251, 2013,
M. Benabdesselam, et al., IEEE TNS, 61(6) 3485, 2014.
g-rays, X-rays, fusion and fission neutrons, protons
High Dose Rate monitoring : Radioluminescence with O2 loaded fibersD. Di Francesca et al., Applied Physics Letters, 105, 183508, 2014
This technique offers dosimeters resistant to high TID levels (MGy)
Proton flux monitoring : RIL + OSL with Ce-doped glassesS. Girard et al., IEEE TNS, in press, 2016
This technique permits to monitor the flux with ms resolution
0 2E6 4E6 6E6 8E6 1E70.00
0.02
0.04
0.06
0.08
0.10
63MeV
48MeV
57MeV
35MeVRIL
(arb
. u
nit
s)
Proton flux (p/(cm².s-1))
a) Ce-doped sample
y= 8.28E-9x
(Pearson's r=0.99861)
0 100 2000.00
0.05
0.10
0.15
0.20
PM
T o
utp
ut
sig
na
l (V
)
Time (s)
63 MeV irradiation
OSL Laser probe ON
PMT noise level
(b) Ce-doped
25 mm
And the Proton fluence too…S. Girard et al., IEEE TNS, in press, 2016
This technique permits to monitor the fluence by integrating the flux
0.0 5.0E8 1.0E9 1.5E9 2.0E9 2.5E90
2
4
6
8
10
12
14
16
18
20
35 MeV
48 MeV
57 MeV
63 MeV
iRIL
(arb
. u
nit
s)
Proton fluence (p/cm²)
b) Ce-doped sample
y=8.625E-9x
(Pearson's r=0.99928)
Perspectives
Online & spatially-Resolved Dose monitoring : through RIA
Radiation sensitive fiber: RIA= f(D)
OTDR measurements
Dose profile extraction
I. Toccafondo, PhD thesis, 2015
Coupled with OFDR instead of OTDR increase of spatial resolution maybe possible
Part 4: Future Challenge
Improve our fundamental knowlege about the generation and recovery mechanisms of radiation-induced point defects
Today, the most efficient way to identify a point defect and its associated optical properties is to combine different spectroscopic techniques
In fact, all techniques present some limitations (online?, spatially-resolved?, paramagnetic?) and such assignments remain very difficult
Is it the right moment to launch such a coupled approach?
“…In both fields, there is a need to further develop models that predict the optical changes induced by the radiation and
particularly the multiscale modeling based on ab initio calculation approach. This is a challenging step toward a deeper
understanding of radiation effects in silica-based materials…An accurate control of the fabrication parameters of the optical
fiber is important and requires close collaboration of the researcher, the fiber supplier and the fiber manufacturer…”
Breakthrough may be possible by developing a multiscale simulation chain allowing to reproduce and predict radiation effects in silica glass
Rev. Scientific Instruments, 79(10), 10F304, 2008
Building and Validation of the coupled experiments/simulation approach
Experimental ToolsRPE, Absorption,
luminescence,
Raman, T,…
Confocal microscopy,
cathodo, EMPA
Radiation tests
Fiber-based system
response
Ab initio: DFT
+ post DFT (GW, BSE)
Monte Carlo - Diffusion Guided Optics
PSO optimization
I. Atomic scale
II. Microscopic scale
III. Device Scale
Simulation Tools
S. Girard, et al. IEEE TNS, 55(6) 3743-3482, 2008 S. Girard, et al. IEEE TNS, 55(6) 3508-3514, 2008N. Richard, et al. IEEE TNS, 1(4), 1819 - 1825, 2014
The methodology to obtain OA, Lum and EPR signatures of point defects is now validated
“Perfect” Pure silica core supercells have been generated
by Molecular Dynamics
These cells are then studied within the DFT framework
(PWSCF code)
Ge-doped cells have been elaborated from the pure silica
cell by substituting a Si by a Ge
Oxygen vacancies (ODC) are generated by removing one
of the 72 O inside the cell and relaxing the matrix
Post-DFT theories as GW approximation and BS equation
are used to obtain the right band gap, defect levels and
optical properties).
Additional codes are used to calculate the EPR signature
of the obtained structureS. Girard, et al. in « Ionizing Radiation Effects in Electronics » Eds Gerardin & Bagatin, CRC Press, 2016
And first insights about the nature of Si and Ge-related defects have been recently obtained
The optical and electronic properties of
SiODC(I) and GeODC(I) and E’ centers
The probable structure and EPR signatures of
Ge(2), E’a, GLPC and their interaction
mechanisms
The nature, OA, Lum and EPR signatures of
ODC centers in pure or Ge-doped silica
N. Richard, et al. IEEE TNS, 1(4), 1819 - 1825, 2014L. Giacomazzi, et al. Physical Review B, 90, 014108 2014
L. Giacomazzi, et al. OMEX, 5 (5), 1054-1064, 2015
L. Giacomazzi, et al. PRB submitted, 2016
Conclusions
Optical fibers are quickly integrated in facilities encountering radiations
Future challenges concern the functionalization of these fibers to monitor parameters such as T, strain, pressure, liquid level, vibrations,….
FBGs, Brillouin, Raman, Rayleigh-based sensors….
Overcoming these future challenges will be possible through a coupled simulation/experiments approach to identify/predict the basic mechanisms describing the radiation effects in dielectrics
The fundamental knowledge, developed experimental or simulation tools of the radiation effects community can bring new insights about the nature of point defects present into optical fibers or allow to tune the optical properties of silica glasses
Non Permanent (2015-2016)Adriana Morana, Post-Doc, HOBAN EU projectDiego di Francesca, Post-Doc, CEA DAM Antonino Alessi, Post-Doc, UJM Imène Reghioua, PhD, UJMAyoub Ladaci, PhD, iXBlueCamille Sabatier, PhD, iXBlueIsabelle Planes, PhD, ANDRAThomas Blanchet, PhD CEA DRTBlaz Winkler, PhD Nova GoricaTimothé Allanche, PhD, UJMChiara Cangialosi, PhD ANDRA NOW @ CERNSerena Rizzolo, PhD AREVA, NOW @ ISAE
Thank you for your attention !
Permanent StaffAziz BoukenterYoucef Ouerdane, Emmanuel Marin