Variations d’indice de réfraction athermiques dans les

$Page 1: Variations d’indice de réfraction athermiques dans les$
JNCO - Optique Grenoble 2007

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JNCO – Optique Grenoble 2007, 3-5 juin 2007

Variations d’indice de réfraction athermiques dans les systèmes laser solides

fortement pompés

R. Moncorgé, J.L. Doualan, P. CamyCentre Interdisciplinaire de Recherches Ions et Lasers (CIRIL-MIL)

UMR 6637 CEA-CNRS-ENSICAEN, Université de Caen, [email protected] ; website: www.ganil.fr/ciril/

O. N. Eremeykin, O. L. AntipovInstitute of Applied Physics of the Russian Academy of science,

46 Ulyanov Street, Nizhny Novgorod 603950, Russia


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Contexte

INTAS program 03-4893 (laser systems based on Nd3+, Yb3+

and Cr3+ doped materials)

Inst. Appl. Phys. Nizhny-Novgorod (O.Antipov) Stepanov Inst.(E.Ivakin), Int. Laser Center (N.Kuleshov) MinskGPI Moscow (I.Shcherbakov) Imperial College of London (Damzen)


- MIL Réseaux holographiques dynamiquesinduits par laser: réseaux de phase (dispersif)

ou réseaux de gain ?

M1 E2

M2 E4

E1

E4

E3

Nd:YAG

PC-mirror

Flash, Diode Pumping

Self-organized laser systemsbased on strongly pumped rare-earth doped laser materials

Eremeykin, Antipov, Damzen, Opt. Lett. 2004 Sillard, Brignon, Huignard, IEEE J.Q.E.1998


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Catunda et al, Appl. Opt. 1986, Weaver, Payne, Phys. Rev. B 1989 → Cr3+

Powell, Payne et al, Phys. Rev. B + Opt. Lett. 1990 → Nd3+

PexcLR Nf απχ Δ=Δ 22πσλχ 4/,Im gaexcNn Δ=ΔPhase contributionAbs/Gain contribution

excN number of excited active ions

322 +

=nfL

Lorentz local correction factor

PαΔ polarizabilityvariationga,σΔ Abs./Gain

cross-section

Réseaux holographiques dynamiquesinduits par laser: réseaux de phase (dispersif)



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Passilly et al, JOSA B 2004 + Opt. Com. 2006 → Cr3+

Margerie, Moncorgé, Phys. Rev. B 2006 → Nd3+

PexcLR Nf απχ Δ=Δ 22πσλχ 4/,Im gaexcNn Δ=ΔPhase contributionAbs/Gain contribution

excN number of excited active ions

322 +

=nfL

Lorentz local correction factor

PαΔ polarizabilityvariationga,σΔ Abs./Gain

cross-section

Réseaux holographiques dynamiquesinduits par laser: réseaux de phase (dispersif)



- MIL Interferometric measurementsunder flash and diode pumping in the case of Nd:YAG

Large non-thermal refraction index

variations (Δn>10-6)

observed in Nd3+:YAG underdiode and flash pumping

Antipov et alIEEE J. Q.E. 39 (2003)


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Refraction index variationsdue to

populations of metastablelevels

4F3/2, 2P3/2, 4D3/2, 2F(2)5/2

5d

4f

E cm-1

26000 2P3/2

4F3/2

4I11/2 4I9/2

2F(2)5/2

0

2100

11500 12500

4D3/2

4G7/2 19000

28000

38000

54000

59000

62500

52000

70000

61000

43000

68000

46000

4F5/2 2H9/2

4G11/2 4G9/2

Laser1.06µm

Flashpump

Diode808nm

)2(2 F

2F(2)5/2

4f25d

4f3but

Case of Nd:YAG


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5d

4f

E cm-1

26000 2P3/2

4F3/2

4I11/2 4I9/2

2F(2)5/2

0

2100

11500 12500

4D3/2

4G7/2 19000

28000

38000

54000

59000

62500

52000

70000

61000

43000

68000

46000

4F5/2 2H9/2

4G11/2 4G9/2

)2(2 F

2F(2)5/2

Refractive index changes Δnof purely dispersive origin

associated withvariations of polarizabilities Δαp

of the ions in theirground- and excited energy levels

due to the existence of strong

(electric-dipole allowed)4f3 ↔ 4f25d

absorption bands

Case of Nd:YAG


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Outline

Result of theoretical and experimental study in the case of Nd3+:YAG and Comparison with interferometric and 4-wave mixing

Contribution of Ligand to Metal Charge Transfer (LMCT) in the case of Yb3+:YAG

Study of other Yb3+ doped laser crystals: GGG, KGW, KYW, YVO4

Summary and conclusion


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)()()( ννν gex nnn −=Δ

exLP N

nf

n )(2

)( 2

νπ

να Δ=Δ

Changes of refractive index Δn and polarizability Δαp associated with 4f3 →4f25d

absorption bands

5d

4f

E cm-1

26000 2P3/2

4F3/2

4I11/2 4I9/2

2F(2)5/2

0

2100

11500 12500

4D3/2

4G7/2 19000

28000

38000

54000

59000

62500

52000

70000

61000

43000

68000

46000

4F5/2 2H9/2

4G11/2 4G9/2

)2(2 F

2F(2)5/2

4f25d

4f3

( )∫∞

−

−=Δ

0 222 ''

)'()'(2

)( ννν

νσνσπ

ν dPNn gesaex

( ) 2

',,

22

'0

2

' 32 '9

22')'(ifpidfii

pii D

nn

chd ΨΨ

+=∫ ν

επννσ

Margerie, Moncorgé, Phys. Rev. B74 (2006)

Clausius-Mosotti


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0 5000 10000 15000 20000 25000 300000,0

5,0x10-5

1,0x10-4

1,5x10-4

2,0x10-4

Δn(4I9/2)Δn(4F3/2)

Laser wavelength of 1.064 µm

Δn (4F3/2-4I9/2)

Δn

Wavenumber (cm-1)

Nex=1020cm-3

exNxnmn 25107.1)1064( −≈Δ

0 20000 40000 60000 80000 100000 120000 140000

-1,0x10-3

-5,0x10-4

0,0

5,0x10-4

1,0x10-3

Δn(4I9/2)

Δn(4F3/2)

Δn (4F3/2-4I9/2)

Δn

Wavenumber (cm-1)

Nex=1020cm-3

Refractive index changesdue to population of metastable 4F3/2

(Δα4F-4I (1064 nm) ≈ 1.6 x 10-26 cm3)Margerie, Moncorgé, Phys. Rev. B74 (2006)


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exPL Nfn

n )2( 2 απΔ=Δ

Comparison with literature data

Antipov: IEEE J. QE 39 (2003)910; Powell: Opt. Lett. 14 (1989)1204

Δα4F-4I (514 nm) ≈ 2.5 x 10-26 cm3Powell 1989: 4-waves mixing at 514nm

Δα4F-4I (514 nm) ≈ 4.9 x 10-26 cm3

Δα4F-4I (633 nm) ≈ 2.0 x 10-26 cm3

Δα4F-4I (1064 nm) ≈ 1.6 x 10-26 cm3

Δα2F(2)-4I (633 nm) ≈ 10-25 cm3

Antipov 2003: Pump-probe transientinterferometry (pump at 808 nm, probe at633 nm)

Δα4F-4I (633 nm) ≈ 4.0 x 10-26 cm3

Estimation at 1064 nm:

Δα4F-4I (1064 nm) ≈ 3.3 x 10-26 cm3

Δα2F(2)-4I (633 nm) ≈ 1.5 x 10-25 cm3

(modified according to our own data)

Results ofcalculations

Experimental dataand estimates


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exPL Nfn

n )2( 2 απΔ=Δ



Δα4F-4I (514 nm) ≈ 4.9 x 10-26 cm2

Δα4F-4I (633 nm) ≈ 2.0 x 10-26 cm2

Δα4F-4I (1064 nm) ≈ 1.6 x 10-26 cm2

Δα2F(2)-4I (633 nm) ≈ 10-25 cm2


Δα4F-4I (633 nm) ≈ 4.0 x 10-26 cm2


Δα4F-4I (1064 nm) ≈ 3.3 x 10-26 cm2

Δα2F(2)-4I (633 nm) ≈ 1.5 x 10-25 cm2



Calculated values a factor 2 smaller ?


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exPL Nfn

n )2( 2 απΔ=Δ



Δα4F-4I (514 nm) ≈ 4.9 x 10-26 cm2

Δα4F-4I (633 nm) ≈ 2.0 x 10-26 cm2

Δα4F-4I (1064 nm) ≈ 1.6 x 10-26 cm2

Δα2F(2)-4I (633 nm) ≈ 10-25 cm2


Δα4F-4I (633 nm) ≈ 4.0 x 10-26 cm2


Δα4F-4I (1064 nm) ≈ 3.3 x 10-26 cm2

Δα2F(2)-4I (633 nm) ≈ 1.5 x 10-25 cm2



Additional contribution: Charge Transfer (CT) ?


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Position (Jorgensen)

)]()(.[30000 32 +− −≈ NdOE LMCTgsa χχ

2.3)( 2 ≈−Oχ 2.1)( 3 ≈+Ndχ

)167(60000 1 nmcmE LMCTgsa

−≈

Reorganisationof electronic cloud around

excited ion

Ligand → Metal Charge Transfer (LMCT) O2-→Nd3+ in Nd:YAG

5d

4f

E cm-1

26000 2P3/2

4F3/2

4I11/2 4I9/2

2F(2)5/2

0

2100

11500 12500

4D3/2

4G7/2 19000

28000

38000

54000

59000

62500

52000

70000

61000

43000

68000

46000

4F5/2 2H9/2

4G11/2 4G9/2

)2(2 F

2F(2)5/2

4f3

4f25d

CT


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Outline






- MIL Case of Yb:YAG: large refractive index variation under 940 nm diode pumping !

Antipov et al, Opt. Lett. 31 (2006)

0 2 4 6 8 10 12 140.00

0.01

0.02

0.03

0.04

0.05

10%Yb:YAG

1.2 ms 51 ms

time (ms)

inte

nsity

(arb

. uni

t)

ΔαPinterf = (1.9±0.8)x10-26 cm3

at 632.8 nm

Δn ≈ 3.2 to 4.4 x10-6

for a pump fluence of∼ 200mJ/cm2


- MIL Ligand → Metal Charge Transfer (LMCT) O2-→Yb3+

LMCT at 10K in YAG:Yb (Van Pieterson J. Lumin. 2000)

émission

excitation)210(47600(max) 1 nmcmE LMCT

gsa−≈

(photo LULI)


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5d

4f

E cm-1

2F(2)5/2

0

565

10902

4F7/2612785

1062410327

50000

E(cm-1)

CT

Diode940 nm

laser

5d

Position (Jorgensen)

)]()(.[30000 32 +− −≈ YbOE LMCTgsa χχ

2.3)( 2 ≈−Oχ 62.1)( 3 ≈+Ybχ

)211(47400 1 nmcmE LMCTgsa

−≈

Ligand → Metal Charge Transfer (LMCT) O2-→Yb3+


- MIL Polarizability and refractive index variations due to LMCT absorption band

[ ] [ ]⎥⎦⎤

⎢⎣

⎡−

−−Δ−

=Δ −2222

15

()(101.7)(

υυυυυυα

CT

g

CT

exspectP

ffx

exPL Nfn

n απΔ=Δ 22

147600 −≈ cmCTυ

Energy (cm-1)

50

40

30

20

10

0 2F7/2

2F5/2

CT

210 nm(47600 cm-1)

260 nm ?(38460 cm-1)

110250 −≈Δ cmυ

?, exg ff


- MIL Position and cross section of 2F5/2 → CT ESA transition

5d

4f

E cm-1

2F(2)5/2

0

565

10902

4F7/2612785

1062410327

47500

E(cm-1)

CT

Diode940 nm

laser

1)1025047600( −−≈ cmE LMCTesa

)268( nm

Estimated position

200 250 300 350 4000.0

0.4

0.8

1.2

1.6

Time Delay: 3 μs 220 μs 620 μs

5%Yb:YAG

Wavelength (nm)

Ln(I u/I

p)

Measured ESA spectrum

σesa(265 nm) ≈ 1.1 x 10-18 cm2

ESA


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001.001.0)(1013.12

19

±≈≈ ∫ λλσλ

dxf esaex

Variations de polarisabilité et variations d’indice dues à la bande LMCT ?

approximation: exg ff ≈

326104.2)633( cmxnmspectP

−≈Δα

326102)1030( cmxnmP−≈Δα 6107.2)1030( −≈Δ xnmn

for a pump fluence of ∼200mJ/cm2

326int 10)8.09.1()633( cmxnmerfP

−±≈Δα


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Outline






- MIL Study of other Yb3+ doped laser crystals:GGG, KGW, KYW and YVO4

0 1 2 3 4 50

5

10

15

10 ms

10%Yb:KGW

380 µs

Inte

nsity

(arb

. uni

t)

Time (ms)

0.0 0.2 0.4 0.6 0.8 1.00

10

20

30

40

50

60

2%Yb:YVO4

288/2=144 µs

Inte

nsity

(arb

. uni

t)

Time (ms)

Ivakin et al, Appl. Phys.B 86 (2007)

Δn ≈ 3 to 4 x 10-6

Δn ≈ 2 to 5 x 10-6


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200 250 300 350 4000

1

2

3

4

ESA x 5

GSA

Yb3+:GGG

Opt

ical

den

sity

, ln(

I u/Ip)

Wavelength (nm)

ESA spectra of Yb3+:GGG and Yb3+:KGW

275 300 325 350 375 4000.0

0.5

1.0

1.5

ESA

GSA

10%Yb:KGW

Opt

ical

den

sity

, Ln(

I u/Ip)

Wavelength (nm)


- MIL CT absorption band in Yb3+:KGW

1410502/72

−≈+= cmesaCT F υυυ

5d

4f

E cm-1

2F(2)5/2

0

565

10902

4F7/2612785

1062410327

41000

E(cm-1)

CT

Diode940 nm

laser

30750 cm-1

(325 nm)

40000 35000 30000 25000

0.0

0.5

1.0

1.5

245 nm

CTabsorption

GSAYb:KGW

Opt

ical

den

sity

, ln(

I uI p)Wavenumbers (cm-1)

+−+ → 65

22

34 , dpf WOYb between mixed

orbitals


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1410502/72

−≈+= cmesaCT F υυυ

5d

4f

E cm-1

2F(2)5/2

0

565

10902

4F7/2612785

1062410327

41000

E(cm-1)

CT

Diode940 nm

laser

30750 cm-1

(325 nm)

40000 35000 30000 25000

0.0

0.5

1.0

1.5

245 nm

CTabsorption

GSAYb:KGW

Opt

ical

den

sity

, ln(

I uI p)Wavenumbers (cm-1)

002.0023.0)(1013.12

19

±≈≈ ∫ λλσλ

dxf esaex

Polarizability variation in Yb3+:KGW


- MIL Polarizability variation in Yb3+:KGW

[ ] [ ]⎥⎦⎤

⎢⎣

⎡−

−−Δ−

=Δ −2222

15

()(101.7)(

υυυυυυα

CT

g

CT

exspectP

ffx

141050 −≈ cmCTυ

Energy (cm-1)

50

40

30

20

10

0 2F7/2

2F5/2

CT

245 nm(41050 cm-1)

325 nm (30750 cm-1)

110250 −≈Δ cmυ

325102.1)633( cmxnmspectP

−≈Δα

five times larger than in Yb:YAG

exg ff ≈

Ivakin et al, Appl. Phys.B 86 (2007) → 325.,int 10)633( cmnmdifferfP

−≈Δα


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Conclusion

Réseaux d’indice de différentes origines:- Réseaux d’absorption/gain- Réseaux de phase (bandes fd and CT)

Cas des matériaux dopés Nd3+: contributions fd (+CT); Réseaux absorption/gain dominant mais contribution de réseaux de phase augmentant non-lineairement avec puissance de pompage – suite à population du metastable2F(2)5/2 (ESA + UC) -

Cas des matériaux dopés Yb3+: contributions CT (+ fd); réseau de phase dominant


- MIL Phase or absorption/gain grating ?

pump pump

sondesignal

⎥⎦

⎤⎢⎣

⎡Δ

Δ≈=

ΔΔ

=σ

αυπχχβ

nf

RR PL

gainabs

phR22

/Im

8

0.23 (at 1029 nm) β = 1.1

0.15 (940 nm)β = 18

2

Yb:YAG

0.28 (at 1029 nm)β = 5.5

2.7 (at 1064nm)β = 0.16

16 (980 nm)β = 1

5.9 (à 808 nm) β = 1

103.5

Yb:KGWNd:YAG

)10( 326 cmP−Δα

)10( 220 cmabs−Δσ

)10( 219 cmgain−Δσ


- MIL

Merci pour votre attention

CIRIL – Materials and Laser InstrumentationWebsite: www.ganil.fr/ciril/; see also: http://cmdo.in2p3.fr

Researchers:• A. Braud (Ass. Prof., Univ.)• P. Camy (Ass. Prof. Univ.)• J.L. Doualan (CNRS)•J. Margerie (Prof. Univ.)• R. Moncorgé (Prof. Univ.) • M. Velazquez (CNRS)

PhD students:• L. Bodiou (CEA)• A. Ferrier (DGA)

MS students:• S. Cheffah• M. Edlinger

Engineer and Technician:• A. Benayad• V. Ménard

Documents

Variations d’indice de réfraction athermiques dans les