quel absorbant saturable pour verrouiller en phase...

Quel absorbant saturable pour verrouiller en phase efficacement un laser à fibre de puissance ?

CNRS – UNIVERSITE et INSA de Rouen

Amélie Cabasse 1*, Gilles Martel 1, Dmitry Gaponov 1, Samir Abbas 1, H.T. Nguyen 2, Jean-Louis Oudar 2

1. CNRS-CORIA, UMR6614, Avenue de l’Université BP12, 76801 ROUEN _ St Etienne du Rouvray, France

*. Current address : CNRS-CELIA, UMR5107, 351 Cours de la libération, 33405 Talence, France

2. CNRS-LPN, UPR20, 91460 Marcoussis, France

3. ONERA, French Aerospace Agency, 93322 Palaiseau, France

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ERA-NET Nanoscience

ANR-06-NSCI-0006 - FP 6


Outline

• Mode-locked fiber laser Energy scaling: the role of dispersion in cavitySaturable absorber mirrors

Multiple quantum wells SAM- Description- Linear & Nonlinear characterizations- Harvesting energy/pulse from Mode-locked fiber las er - Experimental configuration of the Er-doped fiber l aser- Numerical simulations : The role of the dispersio n

• Investigation of a new SAM type - Carbon nanotubes- Fabrication of CNT-SAM & Nonlinear characterizatio n- Results in laser cavity- Numerical simulations : The role of SA

• Conclusions

EnergyEnergy SCALING SCALING requestsrequests

ManagingManaging dispersion (n = n(dispersion (n = n(ωω))))


SolitonSoliton ΣΣΣΣββββiL i < 0

StretchedStretched ΣΣΣΣββββiL i < 0 ou ΣΣΣΣββββiL i > 0Dispersion managed Soliton

CPOCPO

New Concept Chirped & Amplified pulses within Oscillator (µJ-Level)

ΣΣΣΣββββiL i > > 0

- GVD, NL, Gain SA--GVD, NL, Gain SA

+GVD, NL, Gain SAAllAll --normalnormal

ΣΣΣΣββββiL i > 0Chirped Pulses

+GVD, NL, Gain AS+GVD

�ββββ2 < 0 (D > 0) : Anomalous dispersion

�ββββ2 > 0 (D < 0) : Normal Dispersion

Mode-locked fiber laser :The role of dispersion

+GVD -GVD, NL, Gain SA

How to self-start mode-locking within Fiber Lasers

SATURABLE ABSORBERSSATURABLE ABSORBERS


CW Regime

Low peak power

Unsaturated Absorber

(at rest !)

Regime with High Losses

Pulsed Regime

High Peak Power

Saturated Absorber

(Excited !! )

Regime with Low losses

Inverse Saturable Absorption

Two – photons Absorption

�� Avoid Q-switching !??

�� NPE NPE �� MQWsMQWs--basedbased�� Nanotubes or Nanotubes or GrapheneGraphene--basedbased ??

Reflectivity

TimeAPL1999-V74-N26 p3927 Kartner TPA in SESAMAPB2000 V70 S41 Kartner Suppression of QSML…


Outline


Multiple quantum wells SAM- Description: Linear & Nonlinear characterizations- Harvesting energy/pulse from Mode-locked fiber las er - Experimental configuration of the Er-doped fiber l aser

Investigation of a new SAM type - Carbon nanotubes- Fabrication of CNT-SAM & Nonlinear characterizatio n- Results in laser cavity- Numerical simulations : The role of SA

• Conclusions• Perspectives

Multiple Quantum wells-based SAM Description & Characterization

MQWs-based SA (from LPN laboratory/Marcoussis-Paris)

1) Linear optical properties (RESONANTRESONANT-SAM)


1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75 1,800,0

0,2

0,4

0,6

0,8

1,0

∆λ∆λ∆λ∆λFWHM

= 28 nm

λλλλ = 1560 nmλλλλR=1548 nm

CC1

1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75 1,800,0

0,2

0,4

0,6

0,8

1,0


= 28 nm

λλλλ = 1560 nmλλλλR=1548 nm

CC1

1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75 1,80

0,0

0,2

0,4

0,6

0,8

1,0

λλλλR=1553 nm


= 27 nm

λλλλ = 1560 nm

CB1

1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75 1,80

0,0

0,2

0,4

0,6

0,8

1,0

λλλλR=1553 nm


= 27 nm

λλλλ = 1560 nm

CB1

1.4 1.5 1.6 1.7 1.8

H4


=40nm


=64nm∆λ∆λ∆λ∆λ

FWHM=69nm


=44nm


=60nm

1520 nm < λλλλR < 1610 nm

Wavelength (µm)

1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80

0.0

0.2

0.4

0.6

0.8

1.0

λλλλRés = 1572 nm

Reflectivity Point 1 ∆λ∆λ∆λ∆λ

FWHM=40 nm

Reflectivity Point 2 ∆λ∆λ∆λ∆λ

FWHM=47 nm

Reflectivity Point 3 ∆λ ∆λ ∆λ ∆λ

FWHM=30 nm

Low

Flu

ence

Ref

lect

ivity

Wavelength (λ) nm

MB7

Measured with 10 ps pulse (reproduced in-cavity cond itions):

MB7

0,1 1 10 100 10000,30

0,35

0,40

0,45

0,50

0,55

0,60

0,65CB1 f

SESAM=8mm f

f ibre out=11mm

filter IN+OUT12-09-11

Rabs user2 (User)Fit of D

Rab

sFluence, µJ/cm2

Rabs calibration - silver mirror - 99% -> 70.3%

Equationy=y=exp(-x*P4)*P1* ln(1+P2/P1*(exp(x*P3)-1))/(x*P3);

D

P1 0,65215 0,00346

P2 0,33979 0,003

P3 0,05151 0,00237P4 3,72372E- 5 2 ,24879E-6

CB1

0,1 1 10 100 10000,50

0,55

0,60

0,65

0,70

0,75

Rabs user1 (User)Fit of E

Rab

s

Fluence, µJ/cm2

H4 fSESAM=8mm ffibre out=11mm

filter IN+OUT

12-09-11

Equ ationy=P1*ln(1+P2/P1*(exp(x*P3)-1))/(x*P3);

E

P1 0,7308 0,00299P2 0,52955 0,00468P3 0,02665 0,00313

H4

∆R

Multiple Quantum wells-based SAM Description & Characterization

MQWs-based SA (from LPN laboratory/Marcoussis-Paris)

2) Non-Linear optical properties


Measured with 1 ps pulse:

1 10 10010

15

20

25

30

35

40

45

50

Ref

lect

ivity

(%

)

Rns

R0

∆R

Fsat

Sample MB7 Sample H4

1 10 1005

10

15

20

25

30

35

40

45

50Sample CB1

F2Fluence, µJ.cm-2

No TPA ! In working region for in-cavity SESAMs

(90% to 95 % energy extracted)

High modulation depth ∆∆∆∆R >30%!


Energy scaling of ML fiber lasers

Experimental configuration

Laser cavity optimizationtoward the

dissipative solitonic(C.P.O.)

regime

�

�

�

�

Erbium-doped fiber (depending on the requested cavity)HOT750αunpumped = 17 dB/m @ 1530 nm / β2 = -1.2 ps²/km @ 1550 nmHOT742αunpumped = 14 dB/m @ 1530 nm / β2 = +35 ps²/km @ 1550 nmOFS80αunpumped = 80 dB/m @ 1530 nm / β2 = +60 ps²/km @ 1550 nm

��

�

�

Dispersion compensation fiber (DCF)β2 = +116 ps²/km @ 1550 nm

Couplers

Varying from 50/50 to 95/05

Max. value of the coupleur: output sides

To extract max. energy/pulse

To decrease fluence on SAM

� � A.Cabasse et al ., Opt. Express 16, 19322 (2008)� � A.Cabasse et al ., Opt. Express 17, 9537 (2009)


MQW’s based SAM – Experimental Results in Laser Cavity

Quasi-All Normal Regime

Lower losses

No mode-locking

HigherΤΤΤΤrelax

Lower Threshold Higher TPA thresh.

High Nonlinearity

A.Cabasse et al ., Opt. Letters, 36 (15th July), 2620, (2011)G.Martel et al ., JOSA B (in preparation)

MQW’s based SAM – Best Results in Laser CavityQuasi-All Normal Regime with new pumping power

R-SAM – CB1

Mode-locked regime : 600 mW < Pp < 1 W (pump power limited)

With MQW-CB1 sample & optimized cavitylength (rep rate: 28 MHz) ββββ2 = +0.27 ps²

Average output Power :205 mW

Energy per pulse :7.1 nJ (rep rate 28 MHz)

Output Chirped Pulse10.4 ps

Dechirped pulse: 515 fs

Spectral width:12.1 nm

0 200 400 600 800 10000

50

100

150

200 with CB1 single pulse

CW

Ave

rage

Pow

er (

mW

)

Launched pump power (mW)

slope efficiency = 21.6%

205 mW

1 / (28 MHz)

0 200 400 600 800 10000

50

100

150

200 with CB1 single pulse

CW

Ave

rage

Pow

er (

mW

)

Launched pump power (mW)

slope efficiency = 21.6%

205 mW

1 / (28 MHz)

-40 -20 0 20 400.0

0.2

0.4

0.6

0.8

1.0 Ppump

=1 W Fit with Sech² Experiment

∆τFWHM

= 1,54x10.4 ps

Inte

nsity

(a.

u.)

Delay time (ps)

-4 -2 0 2 40.0

0.2

0.4

0.6

0.8

1.0 PPump

=1W

Exp.

∆τFWHM

= 1,54x515 fs

Inte

nsity

(a.

u.)

Delay time (ps)1550 1555 1560 1565 1570

0.0

0.2

0.4

0.6

0.8

1.0 CB1

Nor

mal

ized

Pow

er d

ensi

ty

Wavelength (nm)

PPump

=1W

Exp.

∆λFWHM

=

12.15 nm

R-SAM

100% gold mirror DCF Er3+-fiber (0.5m) (1.5m)

WDM

90/10

Pump diode @ 980 nm (1 Watt)

L1

L2 L3

Output 2

Output 1 (50% à 95%)

A.Cabasse et al ., Opt. Letters, 36 (15th July), 2620, (2011)

G. Martel et al .,JOSA B (in preparation)

Coupler 95/5:

3S photonics :

3S photonics.com/


MQW’s based SAM : Searching pump power limit..

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,40,00

0,05

0,10

0,15

0,20

0,25

0,30

Ps.

W

Plaunched, W

slope 21.8 %258 mW

R-SAM


WDM

90/10


L1

L2 L3

Output 2

Output 1 (50% à 95%)

95% to 99%

R-SAM – CB1

Average output Power :260 mW

Energy per pulse :~ 7 nJ (rep rate 36.4 MHz)

Output Chirped Pulse~ 10 ps

Spectral width:~ 10 nm

New pump power !

�Single Transverse Mode @ 980 nm (ALS)

� Several Watts

Coupler 95/5:

2 wattMode-locked regime : 600 mW < Pp < 1.2 W (not pump power limited)

1500 1520 1540 1560 1580 1600 16201E-8

1E-7

1E-6

1E-5

1E-4

1E-3

OS

A s

igna

l, dB

m

λ,nm

Unstable modelockingregime: amplitude jitter and broad spectrum

- too much fluence on SESAM ?

Azur Light System :

azurlight-systems.com

Very new pumping power :


Outline


Multiple quantum wells SAM- Description: Linear & Nonlinear characterizations- Harvesting energy/pulse from Mode-locked fiber las er - Experimental configuration of the Er-doped fiber l aser

Investigation of a new SAM type - Carbon nanotubes- Fabrication of CNT-SAM & Nonlinear characterizatio n- Results in laser cavity- Numerical simulations : The role of SA

• Conclusions• Perspectives


Discovered in 1991 by S. Iijima

S. Iijima, Nature 354, 56 (1991)

A carbone nanotube = Graphene sheet roled in 2D like a cigarette / or spaghetti

n-m = 3p n-m ≠ 3p

Metallic

(1/3)

Semiconducting

(2/3)

21 amanC +=

L ≈ 1 mm

d ≈ 1 nm

2003 : pulsed mode-lock regime

with CNTs deposition on mirror by sputteringS. Set et al., IEEE LEOS Newsletter 17, 11 (2003)

Saturable Absorbers incorporating Nanotubes: SAINTDescription & Characterization

En

erg

ie d

e t

ran

siti

on

, e

V

(lo

ng

ue

ur

d’o

nd

e,

µm

)

(0,5)

(0,62)

(0,82)

(1,24)

(2,4)


0 E

M1

D(E) : M-SWNT

S1

S2

0 E

D(E) : SC-SWNTSemiconducting CNTs (SC-SWNT):

Density of states is null around Fermi

level (like all semiconductors) � PLMetalic CNTs (M-SWNT):

Density of states are non-zero

�very efficient relaxation rates of the

carriers � no PL

H. Lin et al., Nature Materials 9, 235 (2010)

H. Kataura et al., Synthetic metals 103, 2555 (1999)

Diagramme de Kataura

Diamètre des nanotubes (nm)

Saturable Absorbers incorporating Nanotubes: SAINTDescription & Characterization


500 1000 1500 20000,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

900 nm

Opt

ical

den

sity

Wavelength (nm)

1555 nm

Nanotubes 'ablation laser'

500 1000 1500 2000

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

Wavelength (nm)

Nanotubes 'CVD - CoMoCat'

1030 nm576 nm

1555 nm

Opt

ical

den

sity

500 1000 1500 20000,2

0,4

0,6

0,8

1,0

1,2

1,4

Wavelength (nm)

Opt

ical

den

sity Nanotubes 'arc électrique –

carbon solution'

1555 nm

1020 nm 1845 nm

Collaboration with ENS, Cachan & ONERA

Saturable Absorbers incorporating Nanotubes: SAINT

1/Linear characterization (Absorption spectroscopy_FTIR)� Measurements of the Van-Hoove (1D) transitions

of each CNTs layer

1/50

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http://www.sfive.fr

ERA-NET Nanoscience

ANR-06-NSCI-0006 - FP 6

500 1000 1500 20000,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

1165 nm

Opt

ical

den

sity

Wavelength (nm)

Nanotubes 'HiPCO'

1310 nm


1 10 100 1000 1000062

64

66

68

70

72

74

76

78Ablation laser

(V20-60gouttes)Fit

Réf

lect

ivité

(%)

Fluence (µJ/cm²) 0,01 0,1 1 10 100

15,0

15,5

16,0

16,5

17,0

17,5

18,0

18,5

19,0

19,5

Réf

lect

ivité

(%)

Fluence (µJ/cm²)

Ablation laser (V90-100gouttes)Fit

1 10 100 1000 100004

6

8

10

12

14

16

18

20

Réf

lect

ivité

(%)

Fluence (µJ/cm²)


0,01 0,1 1 10 10017,5

18,0

18,5

19,0

19,5

20,0

20,5

21,0

21,5

Réf

lect

ivité

(%)

Fluence (µJ/cm²)

HiPCO (50gouttes)Fit

50

Saturable Absorbers incorporating Nanotubes: SAINT2/ Non-linear characterization


1 10 100 1000 1000062

64

66

68

70

72

74

76

78Ablation laser

(V20-60gouttes)Fit

Réf

lect

ivité

(%)

Fluence (µJ/cm²) 0,01 0,1 1 10 100

15,0

15,5

16,0

16,5

17,0

17,5

18,0

18,5

19,0

19,5

Réf

lect

ivité

(%)

Fluence (µJ/cm²)


1 10 100 1000 100004

6

8

10

12

14

16

18

20

Réf

lect

ivité

(%)

Fluence (µJ/cm²)


0,01 0,1 1 10 10017,5

18,0

18,5

19,0

19,5

20,0

20,5

21,0

21,5

Réf

lect

ivité

(%)

Fluence (µJ/cm²)

HiPCO (50gouttes)Fit

Sample Name R0

(%)Rns

(%)∆∆∆∆R(%)

Fsat

(µJ.cm -²)F2

(µJ.cm -²)

V20-60 drops 65 76,6 11 120 2.104

V50-100drops 6 16 10 400 5.104

V90-100drops 15 18,6 3 5 1.104

HiPCO 19 21 2 2 600

Saturable Absorbers incorporating Nanotubes: SAINTNon-linear characterization

D. Gaponov, A. Cabasse, G. Martel , JOSA B (in pr eparation)

G. Martel et al. Laser Physics journal (2012) from Sarajevo LPHYS ’11 this invited talk

-100 -50 0 50 100

0,0

0,2

0,4

0,6

0,8

1,0

Inte

nsité

(u.

a.)

Temps (ns)CNRS – UNIVERSITE et INSA de Rouen

02

20 .1 P

T

L

L

NL

D γβ

==

Limited energy due to

SOLITONIC AREA THEOREM

AnomalousAnomalous Dispersion Dispersion regimeregime

β2 = -0,1 ps² (« True » soliton)

Frép = 16 MHz

CNTs –Laser Ablation V20-60 gouttes

For Pumping power > 31 mW

MULTIPLE PULSING

Saturable Absorbers incorporating Nanotubes: SAINTExperimental results in laser cavities

R-SAM


WDM

90/10


L1

L2 L3

Output 2

Output 1 (50% à 95%)



R-SAM


WDM

90/10


L1

L2 L3

Output 2

Output 1 (50% à 95%)


1520 1540 1560 1580 16000,0

0,2

0,4

0,6

0,8

1,0

Inte

nsité

(u.

a.)

Longueur d'onde (nm)

∆λFWHM

= 30,1 nm

-100 -80 -60 -40 -20 0 20 40 60 80 1000,0

0,2

0,4

0,6

0,8

1,0

∆τFWHM

= 1,54x6,1 ps

Inte

nsité

(u.

a.)

Temps de retard (ps)Performance (@23 mW)

Stretched Pulse duration = 6,1 ps - Spectral bandwidth = 30,1 nm

� dechirpable down to = 184 fs

Average Output Power = 1,6 mW � Eimp = 100 pJ

Saturable Absorbers incorporating Nanotubes: SAINTExperimental results in laser cavities

Dispersion managed Dispersion managed solitonicsolitonic regimeregime

β2 = +0.02 ps² « stretched pulse regime »)Frep = 15.6 MHz

Pulsed Regime for Pumping power of : 10 mW < Pp < 23 mWTheoretical deTheoretical de --Chirped Chirped PulsePulse

-3 -2 -1 0 1 2 30.0

0.2

0.4

0.6

0.8

1.0

Inte

nsity

(a.

u.)

Delay Time (ps)

1.54x184 fs


∆∆∆∆T1/e = 320 fs

HiPCO

@ 1,55 µm

0 1 2 3 4 5 6 70.0

5.0x10-4

1.0x10-3

1.5x10-3

2.0x10-3

2.5x10-3

∆T

Temps (ps)

∆∆∆∆T1/e = 390 fs

Laser Ablation

@ 1,55 µm

∆∆∆∆T1/e = 200 fs

HiPCO

@ 1,32 µm

Interpretation : influence of contacts in between CNTs

P. A. Obraztsov et al., J. of Nano-electronics & Optoelectronics 4, 227 (2009) - H. Nong et al., Applied Physics Letters

96, 061109 (2010) - J.-S. Lauret et al., Physical Review B 72, 113413 (2005)

SEM Images


0 500 1000 1500 2000-0,2

0,0

0,2

0,4

0,6

0,8

1,0

∆ T/T

Temps, fs

Isolated CNTs � τrelax= 3,9 psBundles of CNTS � τrelax= 380 fs

Ten timesfaster !!

Collaboration with ENS, Cachan & ONERA


nsR

Quenching in between CNTs into SAINTs leads to :

� Ultra-short Relaxation Time

�Too low modulation depth to serve as an efficient SAM for self-starting

fiber oscillators with high gain / losses (i.e. DS_CPO)

� So no High energy pulsesup to date with CNTs

N.N.Akhmediev et al., Opt. Lett. 23, 280 (1998)

]))(1

(exp[)(2

dtE

tE

Ttf

SAMR

+= ∫

[ ]( ) ( ) ( )out in linI t I t R R q t= + ∆ −R

R 1q( t ) [ f ( t )dt 1 ]

f ( t ) T

∆= +∫avec :

→

Time-dependant Saturable Absorber 0

R SAM

( t ) ²q( t ) q( t ) qq( t )

t T E

ψ∂ −= − −∂


-20 -10 0 10 200,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

∆R=0.35

Rlin

=0.15

Réf

lect

ivity

Time

Trelax

=100Tp |E

MAX|²=10E

SAM

Trelax

= Tp |E

MAX|²=10E

SAM

Trelax

=0,1 Tp |E

MAX|²=10E

SAMR

ns=0.5




Conclusions

With MQWs based SA:�Generation of ultrashort pulses in a highly normal dispersion regime at 1.5 µm

� More than 7 nJ energy per pulse / 205 mW average power at 28 MHzWith CNTs based SA:�ML regime in a solitonic & in a stretched-pulse regime

� energy per pulse is limited (350 pJ) !� at higher pump power : multiple pulsing regime� BUT non-resonance of the CNTs-SAM allows 30nm/185

fs dechirped pulse in stretched pulse regime

� No ML regime in a highly normal dispersion regime� Limited by too fast recovery time inherent to bundle CNTs contacts� Up to date, MQWs-SA technology seems more efficient than CNTs-SA to generate high-energy pulses from fiber l asers

Thank you for your Thank you for your attentionattention

Questions ?

Contacts: [email protected] / [email protected]@celia.fr

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