Radiation Effects on Optical Fibers and Fiber-based Sensors Radiation Effects on Optical Fibers and

Radiation Effects on Optical Fibers and Fiber-based Sensors

Recent Advances and Future Challenges

Sylvain Girard

sylvain.girard@univ-st-etienne.fr

Phone: +33 (0) 477 915 812

CERN Seminar, Geneva, Sept. 27th, 2016 1

mailto:sylvain.girard@univ-st-etienne.fr

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 fibers Microstructured optical fibers  Hollow core optical fibers  Plastic optical fibers

In this talk, we focus on silica-based optical fibers for which the 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

10 0

10 2

10 4

10 6

10 8

10 10

10 12

Queue d'Urbach

Défauts (?)

Défauts induits par irradiation

Impureté OH

Diffusion ( -4 )

A tt

é n

u a ti

o n

o p

ti q

u e (

d B

/k m

)

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

p ti

ca l a

tt e

n u

at io

n (

d B

/k m

)

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 Effects on 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

Courtesy B. 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

Electrons Neutrons

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 4000 0

3

6

9

12

15

R IA

( d

B /k

m )

Time (s)

SM_GeP

SM_Ge

0.8 MeV neutrons

5x10 13

n/cm²

1550nm

0 500 1000 1500 2000 2500 3000 3500 4000 0

3

6

9

12

15

R IA

( d

B /k

m )

Time (s)

SM_GeP

SM_Ge

0.8 MeV neutrons

5x10 13

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 0.01 0.0

0.5

1.0

1.5

2.0

2.5

R IA

( 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 hardened optical 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

R I A

[ d

B /

m ]

Low OH silica with H2

R I A

[ d

B /

m ] POSITIVE IMPACT

NEGATIVE IMPACT

 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-rays 14 MeV n g-rays

Monte Carlo Simulation of dose a