M. Vivona1,3,4, S. Girard1,2, C. Marcandella2, E. Pinsard3, A. Laurent3, T. Robin3, B. Cadier3, M. Cannas4, A. Boukenter1, Y. Ouerdane1

1

Laboratoire Hubert Curien, UMR CNRS 5516,Saint-Etienne (France)

2

CEA, DAM, DIF, Arpajon (France)

3 iXFiber SAS, Lannion (France)4 Università

di Fisica, Palerme (Italie)

1

1.

Context of our investigation

2.

Experimental details : 

3.

Results  related to on‐line characterization

4.

Results related to spectroscopic characterization

5.

Conclusions

Active and passive on‐line measurements under ‐irradiation (CEA  Arpajon ‐

Paris)

2

Rare 

Earth 

(RE)‐doped 

fibers 

used  as active medium

in optical amplifiers.

Schematic setup for an  Erbium/Ytterbium‐Doped Fiber 

Amplifier (EYDFA)

1/2

2

Rare 

Earth 

(RE)‐doped 

fibers 

used  as active medium

in optical amplifiers.

Schematic setup for an  Erbium/Ytterbium‐Doped Fiber 

Amplifier (EYDFA)

evaluation of the radiation effects on  the properties of the amplifiers

Total Dose: 0.1 – 10 kGy

Dose‐Rate: 10‐5 – 10‐1

mGy/s

Civil Appl

Military Appl

Space Appl

RE‐doped fibers

integrated in amplifier  operating in space environment 

1/2

4

Most of previous works dedicated to understand attenuation mechanisms were  performed  in passive configuration

(without pumping of RE ions during the test). 

√

G.M. Williams et al., IEEE TNS 45 (1998) 1531      √

B. Fox, IEEE TNS, 57 (2010) 1618 

Fewer experiments characterized

RE‐optical  fibers in active configuration

they show a high degradation in radiative  environment.   

M. Alam, et al. OSA/OFC2007, paper OMF4J. Ma, et al., Optic Express, 17(18),15571, 2009

No amplification No Amplification (amplifier gain = 0) at 120, 

200 or 500 Gy.

Aim: understanding of the physical mechanisms responsible for the signal  degradation and evaluation of the hardening treatment efficiency.

0 100 200 300 400 500-10

0

10

20

M. Alam (0.1 Gy/s)

M. Alam (0.2 Gy/s)

J. Ma (0.4 Gy/s)

 

 

Am

plifi

er G

ain

(dB

m)

Dose (Gy)

3

2/2

4

Pump

propagation in the inner cladding (pure silica). Signal propagation in the core (RE‐co‐doped phosphosilicate glass).

From previous works, Ce‐codoping is considered as an hardening treatment for  irradiated silica samples (glass and optical fibers).

Evaluation of Ce‐codoping and H2‐loading effects on optical amplifier in  radiative environment.

Inner Cladding

RE doped core

Fiber cross section

6

Pumping of the Yb3+‐ions.

Amplifier configuration

(counter-pumped scheme) under –ray radiation.

Radiation chamber

Pompe

PumpLaser Diode (MM) at

915 nm

Signal Laser Diodeat

1545 nm

‐ray radiation at 1.2MeV.

Dose‐rate= 3 mGy/s.

Total dose up to 800  Gy.

Room temperature.

PWM

5

7

0 1 2 3 4 5 6 7

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Lase

r Out

put P

ower

at 1

.5 µ

m (W

)

Pump Power (W)

A#1 (with fiber I(PYbEr) A#3 (with fiber J(PYbErCeHigh)

The standard fiber I(PYbEr) and the Ce‐codoped fiber J(PYbErCeHigh)  have the same  performance in terms of amplification of the 1545nm input signal

.

Laser output power (at 1.5 µm) vs

pump power (at 915 nm)

6

Amplifiers based on fiber I   and fiber J start from the 

same conditions.

8

Fiber

I  degradation

~3 times higher than  fiber J (at 400 Gy).

Fiber M slightly improved, highlighting a proportional dependence of the hardness 

on the Ce‐content.

Fiber J

degradation at 800Gy of ~15% 

0 100 200 300 400 500 600 700 8000.0

0.2

0.4

0.6

0.8

1.0

 A#1 (Fiber I(PYbEr), no Ce)

 A#2 (Fiber M(PYbErCelow))

 A#3 (Fiber J(PYbErCehigh))

Nor

mal

ized

Pow

er a

t 154

5 nm

Dose (Gy)

7

Fiber

I

degradation

~3 times higher than  fiber J (at 400 Gy).

Fiber M slightly improved, highlighting a proportional dependence of the hardness 

on the Ce‐content.

Fiber J

degradation at 800Gy of ~15% 8

0 100 200 300 400 500 600 700 8000.0

0.2

0.4

0.6

0.8

1.0

 A#1 (Fiber I(PYbEr), no Ce)

 A#2 (Fiber M(PYbErCelow))

 A#3 (Fiber J(PYbErCehigh))

Nor

mal

ized

Pow

er a

t 154

5 nm

Dose (Gy)

Fiber Ih and

Fiber Jh deterioration only  after a threshold of~ 200 Gy.

Fiber Jh

also

in hydrogenated fibers, Ce  improves the fiber amplifier performance  under irradiation.

0 100 200 300 400 500 600 700 8000.90

0.92

0.94

0.96

0.98

1.00Hydrogenated fibers

 A#1h (Fiber I(PYbEr)+H2 load

 

 

Nor

mal

ized

Pow

er a

t 154

5 nm

Dose (Gy)

 A#3h (Fiber J(PYbErCeHigh)+H2 load)

7

9

Radiation Induced Attenuation (RIA) measurements under –ray radiation on fiber L(PCeHigh) and N(P)

and their hydrogenated versions.

Signal Diode (DFB)at

1545 nm

Same source of amplifier configuration

RIA at 1545 nmII.

RIA 1000

÷1650nmIII.

I. RIA at 915 nm

Halogen

Light Source

CCD

PWM

Pump

Diode (MM) at

915 nm

PWM

8

10

0 100 200 300 400 500 6000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 Source at 915 nm

 

 

Rad

iatio

n In

duce

d A

ttenu

atio

n (d

B/m

)

Dose (Gy)

 Fiber L(PCeHigh) Fiber N (P)

RIA measurement to evaluate the matrix response at pump wavelength (915 nm) 

Two fiber-sections involved in the degradation, as the pump radiation propagates

1) mainly in the double cladding (DC) 2) but also it interacts with the core glass

Attenuation stronger for fiber L(PCeHigh)

9

0 100 200 300 400 500 6000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 Source at 915 nm

 

 

Rad

iatio

n In

duce

d A

ttenu

atio

n (d

B/m

)

Dose (Gy)

 Fiber L(PCeHigh) Fiber N (P)

RIA measurement to evaluate the matrix response at pump wavelength (915 nm) 

Two fiber-sections involved in the degradation, as the pump radiation propagates

1) mainly in the double cladding (DC) 2) but also it interacts with the core glass

Attenuation stronger for fiber L(PCeHigh)

- the DC structure is equivalent in the fibers L(PCeHigh)

and N(P); - no optical activity of Ce in this range;-

the P content is slightly different, higher in fiber L than in fiber N.

9this attenuation probably

due to P-defects.

111000 1100 1200 1300 1400 1500 16000.0

0.2

0.4

0.6

0.8 

 

Rad

iatio

n In

duce

d A

tteni

atio

n (d

B/m

)

W avelength (nm)

Total Deposited Dose ~300 Gy Fiber N Fiber L

0 100 200 300 400 500 600 700 8000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6Source at 1545 nm

 

 

Rad

iatio

n In

duce

d At

tenu

atio

n (d

B/m

)

Dose (Gy)

 Fiber N(P) Fiber L(PCeHigh)

RIA at signal wavelength (1545 nm) and in the range 1000 ÷ 1650nm

Only the fiber N(P)

is affected by an high attenuation in this range.

In the NIR domain, presence of the P- related defect P1

after irradiation

In fiber L(PCeHigh), Ce

interacts with P1

sites and/or its precursors, leading to the performance improvement of the

Ce-doped optical fibers.

N.B. : NO Recovery after irradiation

10

1000 1100 1200 1300 1400 1500 1600

0.0

0.2

0.4

0.6

0.8Source Halogen Lamp

Total Deposited Dose ~300 Gy

 Fiber N(P)

 

 

Rad

iatio

n In

duce

d A

ttenu

atio

n (d

B/m

)

Wavelength (nm)

 Fiber L(PCeHigh) Fiber N(P) + H

2‐load

0 100 200 300 400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

 Fiber N(P) + H2‐load

 Fiber L(PCeHigh) + H2‐load

Source laser at 915 nm

 

 

Rad

iatio

n in

duce

d At

tenu

atio

n (d

B/m

)

Dose (Gy)

 Fiber L(PCeHigh) Fiber N(P)

0 100 200 300 400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 Source Laser at 1545 nm

 Fiber L(PCeHigh) Fiber N(P)  

 

Rad

iatio

n In

duce

d A

ttenu

atio

n (d

B/m

)

Dose (Gy)

 Fiber N(P) + H2‐load

 Fiber L(PCeHigh) + H2‐load

At pump wavelength (915 nm):    The H2

‐loading has a positive effect both  for the pump and signal wavelengths. 

At signal range (1000‐1650 nm):

Like 

for 

the 

Ce‐codoping, 

the 

H2‐

loading  limits the P1 center presence.11

Hydrogenated fibers Lh and Nh Green and Blue Curves

13

Study of the microscopic mechanisms at the origin of the behavior of the radiation response.

Confocal Raman Microscopy(source: laser He‐Cd at 442 nm, P~ µW)(detector system: 2400grooves/mm, CCD)

Time‐resolved photo‐luminescence(source: tunable laser Nd:YAG, pulse ~5ns, 10Hz)(detector system: 150grooves/mm, Intensified CCD)

12

13

Transition assisted by the 

phononic population of the 

double bond P=O.

200 400 600 800 1000 1200 1400

0.0

0.2

0.4

0.6

0.8

1.0

Nor

mal

ized

Ram

an In

tens

ityRaman shift (cm-1)

phosphosilicate glass core

Typical

Raman spectrum of  the phosphosilicate glass 

core

REMINDER Why

the P=O double bonds are important

in the Er/Yb codoped fiber:

13

0 2000 4000 6000 8000 10000

0.7

0.8

0.9

1.0

1.1

 Fiber I Fiber N

 

 

Nor

mal

ized

Ram

an In

tens

ity a

t ~13

20 c

m-1

Dose (Gy)

 Fiber J Fiber L Fiber M

RRééponseponse

aux radiations X aux radiations X àà

10 keV 10 keV Fibers with

Ce

Fibers without

Ce200 400 600 800 1000 1200 1400

0.0

0.2

0.4

0.6

0.8

1.0

Nor

mal

ized

Ram

an In

tens

ity

Raman shift (cm-1)

phosphosilicate glass core

Reduction of P=O double bonds after X‐irradiation of ~15% for fiber

without Ce.

Ce-codoping: the interaction between the Ce and the P gives a hardening effect with the preservation of P=O

14

The same effect of preservation noticed in H2-loaded fibers (Ih and Jh)

0 5 10 15 20 25 30 35 40e-4

e-3

e-2

e-1

e0

 Fiber J ‐irradiated (~11.5 ms)

 Fiber I pristine (~10.3 ms) Fiber J pristine (~10.3 ms)

 Fiber I ‐irradiated (~12.7 ms)

 

 

Nor

mal

ized

Lum

ines

cenc

e

Time (ms)

EXC

~ 975 nm

15

Study of the decay kineticsinformation about the ion interaction with its surroundings.

Lifetime of the PL  band peaked at 

~1545 nm, related  to Er3+‐emission 

(4I13/2

→4I15/2

)

Variation higher for fiber I than fiber J. Better radiation response of the  Ce‐codoped fiber.

Fiber I (Ce‐free)Fiber J (Ce‐codoped)

A longer lifetime increases the probability of the ESA occurrence

0 5 10 15 20 25 30 35 40e-4

e-3

e-2

e-1

e0

 Fiber J ‐irradiated (~11.5 ms)

 Fiber I pristine (~10.3 ms) Fiber J pristine (~10.3 ms) Fiber Jh ‐irradiated (~10.6 ms)

EXC ~ 975 nm

 

 

Nor

mal

ized

Lum

ines

cenc

e

Time (ms)

 Fiber I ‐irradiated (~12.7 ms) Fiber Ih ‐irradiated (~12.7 ms)

15

Fiber I (Ce‐free)Fiber J (Ce‐codoped)

The irradiated fiber Ih is affected by the same variation of the

lifetime  value as the fiber I. No variations for the fiber Jh. 

Lifetime of the PL  band peaked at 

~1545 nm, related  to Er3+‐emission 

(4I13/2

→4I15/2

)

Our work points out the positive effect of Ce‐codoping and H2

‐loading on active optical  fiber properties and highlights some microscopic characteristics.

1.

Ce and H2 have a key role in the hardening of the active optical fibers (less degradation of transmitted IR signal).

2.

Presence of P1 centers

in the standard fiber (Ce free or no treated with hydrogen).

3.

Efficiency keeping of the energy transfer between Yb and Er in the Ce-codoped fiber under gamma irradiation thanks to preservation of the P=O double bonds.

4.

No variations of the lifetime values respect to the pristine fibers for the fiber Jh (Ce-codoped and H2-preloaded).

16

Thank you for your attention.

marilena.vivona@univ‐st‐etienne.fr