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Radiation Effects on Optical Fibers and Fiber-based Sensors

Recent Advances and Future Challenges

Sylvain Girard

[email protected]

Phone: +33 (0) 477 915 812

CERN Seminar, Geneva, Sept. 27th, 20161

mailto:[email protected]

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)








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








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