high power fiber lasers emitting at 1030 nm and 976...
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High power fiber lasers emitting at High power fiber lasers emitting at 1030 nm and 976 nm1030 nm and 976 nm
E. CormierE. Cormier
CELIA UniversitCELIA Universitéé Bordeaux IBordeaux I--CNRSCNRS--CEA, CEA,
351 cours de la Lib351 cours de la Libéération Fration F--33405 Talence, France33405 Talence, France
E. Cormier CMDO 2010E. Cormier CMDO 2010
1. Introduction
2. Fiber lasers at 1030 nmn
Sub 300 fs: Fiber CPA
Sub 100 fs: Direct amplification
Sub 10 fs: Few cycles with OPCPA
3. Fiber lasers at 976 nm
Main issues
High power : CW laser
High energy: Q-switch
High peak power: Mode-lock systems
Blue Light
High brightness pumping of Yb-doped materials
OutlineOutline
22
E. Cormier CMDO 2010E. Cormier CMDO 2010
1. Introduction
2. Fiber lasers at 1030 nmn
Sub 300 fs: Fiber CPA
Sub 100 fs: Direct amplification
Sub 10 fs: Few cycles with OPCPA
3. Fiber lasers at 976 nm
Main issues
High power : CW laser
High energy: Q-switch
High peak power: Mode-lock systems
Blue Light
High brightness pumping of Yb-doped materials
OutlineOutline
33
E. Cormier CMDO 2010E. Cormier CMDO 2010
• Large amplification bandwidth• Limited thermo-optical problems• Excellent beam quality• Efficient diode pumping operation• High single pass gain• Large variety of doping ions• Compactness
A revolution in laser technology: fiber lasers A revolution in laser technology: fiber lasers
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E. Cormier CMDO 2010E. Cormier CMDO 2010
Bulk rod
Diode pumped solidDiode pumped solid--state laser evolutionstate laser evolution
HR-Mirror Output coupler
Laser beam
Gain mediumlens
End pumped bulk laser
Output coupler
Gain medium
Laser beam
HR-Mirror
lens
Laser Diode
Side pumped bulk laser
Laser Diode
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E. Cormier CMDO 2010E. Cormier CMDO 2010
rod
Diode pumped solidDiode pumped solid--state laser evolutionstate laser evolution
Stress-induced birefringence
Hot
Cold
Thermal lensing
Low power High power
Beam distortions
Laser1060 nm
E0
E2
E3
E1
Heat
Heat
Pump808 nm
Nd3+
Quantum defect = 24 %
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E. Cormier CMDO 2010E. Cormier CMDO 2010
diskslab fiber
reduced thermo-optical distortions
Diode pumped solidDiode pumped solid--state laser evolutionstate laser evolution
HR-Mirror Output coupler
DiskCooling
Laser DiodeLens
Disk laser
Laser beam
Laser Diode
lens
Fiber
HR-Mirror
Laser DiodeLens
Slab
HR-Mirror
y
z
Slab laser
Fiber laser
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E. Cormier CMDO 2010E. Cormier CMDO 2010
Diode pumped solidDiode pumped solid--state laser evolutionstate laser evolution
Heat is spread over long distances in fibers
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nCore
nCladding
n
Refractive Index profile
Laser radiationPump
Active inner core
• Core size < 10 µm• Requires single mode pumping diodes• Pumping limited to 1 W• Length: 10..100 m (non linear effects)
Not compatible with high power
Standard single mode active fiberStandard single mode active fiber
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E. Cormier CMDO 2010E. Cormier CMDO 2010
nCoating
ncore
ncladding
Laser beam
PumpInner claddingActive core
[1] E. Snitzer et. al., Optical Fiber Communication Conference, PD5, 1988
Outer claddingRefractive Index
profile
n
ØcoØcl
• High power multimode pumping diodes
• but higher core doping: ~ Øco/ Øcl
Double clad fiberDouble clad fiber
1010
E. Cormier CMDO 2010E. Cormier CMDO 2010
Step index Step index vsvs airair--clad clad microstructuredmicrostructured fibersfibers
1111
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Typical Typical microstructuredmicrostructured fibers used in our systemsfibers used in our systems– Large core diameter with
diffraction limited operation
–– Polarization maintaining design for Polarization maintaining design for environmentally stableenvironmentally stable operationoperation
-- AirAir--clad clad microstructures for microstructures for pump propagation pump propagation (NA (NA = 0.6)= 0.6)
Rod type fiber
Flexible fibers
80 80 μμmm (NA < 0.02) (NA < 0.02)
40 40 μμmm (NA < 0.01) (NA < 0.01)
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E. Cormier CMDO 2010E. Cormier CMDO 2010
1. Introduction
2. Fiber lasers at 1030 nmn
Sub 300 fs: Fiber CPA
Sub 100 fs: Direct amplification
Sub 10 fs: Few cycles with OPCPA
3. Fiber lasers at 976 nm
Main issues
High power : CW laser
High energy: Q-switch
High peak power: Mode-lock systems
Blue Light
High brightness pumping of Yb-doped materials
OutlineOutline
1313
E. Cormier CMDO 2010E. Cormier CMDO 20101414D. Strickland and G. Mourou, “Compression of amplified optical pulses,”Opt. Comm. 56, 3, 219 (1985).
Chirp Pulse Amplification
CPA fiber amplifier: sub 300 fsCPA fiber amplifier: sub 300 fs
I =E
A .τReduced peak powerReduced nonlinear effects
E. Cormier CMDO 2010E. Cormier CMDO 20101515
GratingCompressor
Power Amplifier
Pulse picker
Grating stretcher
Isolator
Pre-amplifier
Fiberstretcher
E = 100 µJT = 270 fsf = 300 kHzP = 340 MWΔλ = 7.2 nmPav = 30 W
M2 = 1.3
Y. Zaouter et al, Optics letters 33, 1527 (2008)J. Boullet et al, Optics letters 34, 1489 (2009)
CPA fiber amplifier: sub 300 fsCPA fiber amplifier: sub 300 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
1000 800 600 400 200 0
10
100
1000 1 GW
200 MW
50 MW
500 MW
Effe
ctiv
e Pu
lse
Ener
gy (µ
J)
Pulse duration (fs)
JenaImraCeliaSouthamptonCornellIotaCUOS
100 kHz
Y. Zaouter et al, Optics letters 33, 1527 (2008)J. Boullet et al, Optics letters 34, 1489 (2009)1616
CPA fiber amplifier: sub 300 fsCPA fiber amplifier: sub 300 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
Direct amplification: sub 100 fs
DiodesDiodes60 W @ 976 60 W @ 976
nmnm
Yb:KYWYb:KYWoscillatoroscillator
OI
Transmission Transmission gratinggrating
1740 l/mm1740 l/mm
MicrostructuredMicrostructuredrodrod--type 80/200 type 80/200
fiberfiber
OutputOutput
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Spectrum extends up to 60 nmModulations smoothed out due to amplification
•• Gain: Gain: I(zI(z) = I) = I00 exp(exp(αα.z.z) ) •• SPM: SPM: ωω(t(t) = ) = ωω00 (1(1--LnLn²²/c /c dI/dtdI/dt))•• asymmetric gain asymmetric gain
980 1000 1020 1040 1060 10800.0
0.2
0.4
0.6
0.8
1.0
Inte
nsity
[a.
u]
Wavelength [nm]
980 1000 1020 1040 1060 10800
20
40
60
80
Wavelength [nm]Pr
opag
atio
n di
stan
ce [c
m]
1818
Direct amplification: sub 100 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
-600 -400 -200 0 200 400 6000.0
0.2
0.4
0.6
0.8
1.0
Inte
nsity
[a.
u]
Time [fs]
47 fs8.6 W (0.86 µJ)
-400 -200 0 200 400500
510
520
530
Delay [fs]
SHG
Wav
elen
gth
[nm
]
-600 -400 -200 0 200 400 6000,0
0,2
0,4
0,6
0,8
1,0
Inte
nsity
[a.
u]
Time [fs]
66 fs12.5 W (1.25 µJ)
-400 -200 0 200 400500
510
520
530
Delay [fs]
SHG
Wav
elen
gth
[nm
]
18 MW: 1.25 µJ @ 65 fs
10 MHz
Y. Zaouter et al, Optics letters 33, 107 (2008)Y. Zaouter et al, Optics express 15, 15, 9372 (2007)1919
Direct amplification: sub 100 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
Signal stretcher
Yb Fiber CPA pump
Parametricamplifiers Compressor
Signal source
Pumpsource
FCPA pumped OPCPA : sub 10 fs
2020
E. Cormier CMDO 2010E. Cormier CMDO 2010
CEP stabilized
Modelocked source
Signal stretcher
Yb Fiber CPA pump
Parametricamplifiers Compressor
60%60%
Rainbow
• 7 fs Ti:Sapph Oscillator• 300 nm @ -10dB• CEP stabilized
Signal Pump
20 pJ @ 1030
2121
FCPA pumped OPCPA : sub 10 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
Rainbow Spectral Selection Unit
To NOPA
To FCPA
SHG unit
2222
FCPA pumped OPCPA : sub 10 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
CEP stabilized
Modelocked source
Signal stretcher
Yb Fiber CPA pump
Parametricamplifier Compressor
FCPA Pump
Rainbow signal
To SHG-FROG
BBO Type ISF10 prisms
2323
FCPA pumped OPCPA : sub 10 fs
E. Cormier CMDO 2010E. Cormier CMDO 2010
• Spectrum • Duration
1 μJ68 nm amplified bandwidth @ 720 nm10 fs (3.6 cycles)
-40 -30 -20 -10 0 10 20 30 400.0
0.2
0.4
0.6
0.8
1.0
Δτfield = 10 fs
Aut
ocor
rela
tion
time (fs)
Δτautoco = 14,1 fs
14.1 fs
Δτ field = 10 fs
100 kHz
J. Nillon, et al, CLEO 2009 [CWL3] Baltimore USAJ. Nillon, et al, ASSP 2009, [Post Deadline], Denver USA2424
FCPA pumped OPCPA : sub 10 fs
Δλ = 68 nm
E. Cormier CMDO 2010E. Cormier CMDO 2010
1. Introduction
2. Fiber lasers at 1030 nmn
Sub 300 fs: Fiber CPA
Sub 100 fs: Direct amplification
Sub 10 fs: Few cycles with OPCPA
3. Fiber lasers at 976 nm
Main issues
High power : CW laser
High energy: Q-switch
High peak power: Mode-lock systems
Blue Light
High brightness pumping of Yb-doped materials
OutlineOutline
2525
E. Cormier CMDO 2010E. Cormier CMDO 2010
2F5/2
2F7/2
λp= 976 nm λs=1030 nm
Yb-doped fiber
Configuration 1
Yb-doped fiber lasers operating at 976 nm
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2F5/2
2F7/2
λp= 976 nm λs=1030 nm
Configuration 1
2F5/2
2F7/2
915 nm 1030 nm
Configuration 2
976 nm
Yb-doped fiber Yb-doped fiber
2727
Yb-doped fiber lasers operating at 976 nm
E. Cormier CMDO 2010E. Cormier CMDO 2010
σsabs
σsem
σsem ~σs
abs
Issue # 1 :Transparency:
Bleaching is achieved if :
for a pump intensity of:
%502 ≈+
= ems
abss
abss
Tot
trans
nn
σσσ
2kW/cm30≈
⎟⎟⎠
⎞⎜⎜⎝
⎛−
=
fluoempabs
s
ems
absp
ptransp
hI
τσσ
σσν
σsabs
σsem
Transparency at 1030 nm achieved for inversion ~5% …
2828
Yb-doped fiber lasers operating at 976 nm
E. Cormier CMDO 2010E. Cormier CMDO 2010
Issue #2: Gain competition between quasi and true 3-level laser operation :
βα pGG 72.025.0 9761030 +=
Pump absorption Clad to core area ratio
Rod type U-LMA PCF : 80 / 200 µm
β=6.2 : αp=9 dB => G1030 nm< 50 dB
Φclad=200 µm => Pp ~ several 100W
2929
Yb-doped fiber lasers operating at 976 nm
E. Cormier CMDO 2010E. Cormier CMDO 2010
High power CW laser at 976 nm
Rod type fiber :Rod type fiber :MicrostructuredMicrostructuredDouble clad Yb dopedDouble clad Yb doped8080µµm/200m/200µµmmAbsorption: Absorption: 10 dB/m10 dB/mLength : 1.2 m Length : 1.2 m
1 Pptrans = 11 W
2 β = 6.2, losses = 60 dB Boullet et al., OE 16, 17891 (2008)
3030
E. Cormier CMDO 2010E. Cormier CMDO 2010
0 25 50 75 100 125 150 175 200 225 2500
102030405060708090
100110120
Las
er P
ower
@ 9
76nm
(W)
Pump Power @ 915nm (W)
Slope Efficiency = 48%
Ptreshold= 18W
970 972 974 976 978 980 982 984 9860.0
0.2
0.4
0.6
0.8
1.0
Inte
nsity
Wavelength (nm)
950 960 970 980 990 1000 1010 1020 10301E-5
1E-4
1E-3
0.01
0.1
1
Inte
nsity
(Log
scal
e)
Wavelength (nm)
ASE
35 dB
94 W
M2 = 1.35
977.5 nmEfficiency : Spectrum :
Parasitic lasing suppression :Beam quality :
3131
High power CW laser at 976 nm
Boullet et al., OE 16, 17891 (2008)
E. Cormier CMDO 2010E. Cormier CMDO 20103232
High energy Q-switch laser at 976 nm
MOPA: Master Oscillator Power Amplifier
Oscillator
Amplifier
Acousto-optic modulator
Boullet et al., OL 35, 1650 (2010)
E. Cormier CMDO 2010E. Cormier CMDO 20103333
High energy Q-switch laser at 976 nmO
utpu
t pow
er [W
]O
utpu
t pow
er [W
]
Pump power [W]Pump power [W]
Slope efficiency Slope efficiency ≈≈ 35 %35 %Amplification threshold = Amplification threshold = 27 W27 W
T= 35T= 35µµss
INTERPULSE ASEINTERPULSE ASE78 W @ 190 KHz, 32 ns
1 mJ @ 10 KHz, 12 ns
Or
M2 < 1.4
Boullet et al., OL 35, 1650 (2010)
78 W
E. Cormier CMDO 2010E. Cormier CMDO 20103434
High peak power mode-lock laser at 976 nm
970 972 974 976 978 980 982 9840.00
0.25
0.50
0.75
1.00
Inte
nsity
[a.u
.]
Wavelength [nm]980 1000 1020 1040
-40
-30
-20
-10
0
Inte
nsity
[dB
]
Wavelength [nm]
Δλ1/2 = 5 nm
Δλ1/e2 = 10 nm
30 dB
Mode- Locking: non-linear polarization evolutionAll-normal dispersion
Lhermite et al., OL 35, 3459 (2010)
E. Cormier CMDO 2010E. Cormier CMDO 20103535
Output pulsesOutput pulses Compressed pulsesCompressed pulses
-2 0 2 4 6 8 10 120.0
0.2
0.4
0.6
0.8
1.0
Sign
al
Delay [ps]
Δτ = 1.44 ps = 1.41 x 1.02 ps
0.0 0.5 1.0 1.5 2.0 2.5 3.00.0
0.2
0.4
0.6
0.8
1.0
Sign
al
Delay [ps]
Δτ = 402 fs = 1.41 x 285 fs
Pav = 480 mW
ν = 40.6 MHz
E = 11.8 nJ
Δλ = 5 nm
Δτ = 285 fs
Ecompressed = 6 nJ !!!
Ppeak = 21 kW
50 % compressor efficiency only !! Potentially 37 kW
High peak power mode-lock laser at 976 nm
Lhermite et al., OL 35, 3459 (2010)
E. Cormier CMDO 2010E. Cormier CMDO 20103636
Blue light generation at 488 nm
LBO crystal ωλ/2 λ/4 DM
2ω
High energy fiber laser
59 W @ 977 nm
High energy fiber laser
59 W @ 977 nm
36 % 36 % efficiencyefficiency
16.1 W 16.1 W atat 488 nm488 nm
Boullet et al., Europhoton (2010)
E. Cormier CMDO 2010E. Cormier CMDO 20103737
Blue light generation at 488 nm
Boullet et al., Europhoton (2010)
Applications of high brightness intense sources at 488 nm Replacement of Ar ion lasersLaser surgeryDermatologyBiophotonicsLaser light shows and laser display RGB
E. Cormier CMDO 2010E. Cormier CMDO 20103838
High brightness pumping of Yb-doped materialSingle-mode laser
Multi-mode diode
Single-mode laserMulti-mode diode
Brightness : B =P
S.Ω
E. Cormier CMDO 2010E. Cormier CMDO 20103939
High brightness pumping of Yb-doped material
High brightness optical pumping of Yb materials 900 920 940 960 980 1000 1020 1040 1060 1080
0.0
0.5
1.0
Inte
nsity
[a.u
.]Wavelength [nm]
Yb:Caf2
High power High power fiberfiber laserlaser
High power High power diodediode
Source power [W]
Brig
htne
ss[W
/cm
2 /sr]
E. Cormier CMDO 2010E. Cormier CMDO 20104040
High brightness pumping of Yb-doped material
40 W 40 W
ASE source at 976 nm
TEM00
Up to 40 W
974 976 978 980 9820.0
0.5
1.0
Inte
nsity
[a.u
.]Wavelength [nm]
3 W 15 W 27 W 39 W
E. Cormier CMDO 2010E. Cormier CMDO 20104141
High brightness pumping of Yb-doped material
Small signal gain up to 10 expected with long cristals
E. Cormier CMDO 2010E. Cormier CMDO 2010
People:F. Labaye (Phd)J. Nillon (Phd) G. Machinet (Phd)J. Lhermite (PostDoc)L. Lavoute (PostDoc)C. Medina (Assistant Engineer, CNRS)S. Petit (Research Engineer, CNRS)S. Montant (Research Engineer, CEA)D. Descamps (Research Engineer, CEA)E. Cormier (Professor, University)
Collaborations:HHG group @ CELIAInstitut d’optique (Palaiseau)Institut of physics, Vilnius University, Vilnius, Lithuania (A. Piskargkas)Institut of Applied Physics (IAP), Universität Jena, Germany (J. Limpert)Photonics Institute, Vienna University of Technology, Vienna, Austria (A. Baltuska)ETH, Zurich, Switzerland (U. Keller)KEK, Tsukuba, Japan (T. Omori, J. Urakawa)Clarendon Laboratory, University Oxford, England (A. Wyatt, I. Walmsley)Eolite systems (Bordeaux)Amplitude systèmes (Bordeaux)CEA CESTA4343
C. Aguergaray (Phd)Y. Zaouter (Phd)J. Boullet (Postdoc)