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Generation and characterizationof mid-infrared femtosecond pulses
C. Ventalon(1), K. J. Kubarych(2), J. M. Fraser(3), A. Bonvalet et M. Joffre
Laboratoire d’Optique et BiosciencesINSERM U451 – CNRS UMR 7645
Ecole Polytechnique – ENSTA91128 Palaiseau cedex
http://www.lob.polytechnique.fr
(1) Boston University(2) University of Michigan(3) Queen’s University
Time-resolved infrared spectroscopyMultidimensional spectroscopyVibrational coherent control
Motivations
1. Generation of infrared femtosecond pulses
a) Optical rectification (inverse electro-optic effect))()()( *)2(
0)2( tEtEtP χε=
ωω00 IR
b) Difference frequency mixing)()()( *
12)2(
0)2( tEtEtP χε=
ω
0 ω1 ω2IR
• Optical rectification :2
0)2(
0)2( )()( tEtP χε=
• Propagation :2
)2(2
02
2
2
2
2
2 )(t
tPtE
cn
zE
∂∂
=∂∂
−∂∂ μ
Impulsions infrarouges
Milieunon-linéaire
Impulsionvisible de 12 fs t
P(t)E0(t)
tP
cnLtE
∂∂
ε
)2(
02)( −=
A. Bonvalet et al., Appl. Phys. Lett., 67, 2907 (1995)
Infrared generation using optical rectification
Auto
corr
elat
ion
-400 -200 0 200 4000
0.5
1
1.5
2
Retard [fs] Longueur d'onde [μm]
Inté
nsité
spe
ctra
le
4 8 12 16
Fréquence [THz]50 40 30 20
A. Bonvalet et al., Appl. Phys. Lett., 67, 2907 (1995)
Infrared generation using optical rectification
Frequency mixing : one or two stages ?
OPA800 nm λi = 1.6 to 4.5 µm
λs = 1.6 to 0.97 µm
1) One stage
Simple but less efficient above 4.5 µm due to two-photon absorption
1 10 100longueur d'onde [µm]
TeGaSe
AgGaSeAgGaS2
LiNBO3
RTAKTPKTA
GCOBYCOB
LBOBBOKDP
ZnGeP2
LiIO3
KNBO3
400
nm
10 μ
m
800
nm
5 μm
LiInS2
Transparency of nonlinear materials
OPA800 nm λi = 1.6 to 4.5 µm
λs = 1.6 to 0.97 µm
1) One stage
λIR=5 to 20 µm OPA
λi = 1.6 to 2.4 µm
DFG
2) Two stages
800 nm
λs = 1.6 to 1.2 µm
Simple but less efficient above 4.5 µm due to two-photon absorption
Frequency mixing : one or two stages ?
Delay τ
signal
idler
IRGaSe LWP filter
Phase matching
Pump : 2nd stage
laser: HurricaneSpectra Physics100fs @ 800 nm
0.8 mJ1 kHz
2%
BBO
calcitePhase matching
10%Pump : 1st stageSapphire
continuum
Signal + idler
Kaindl et al., JOSA B 17, 2086 (2000)Ventalon et al., JOSA B 23, 332 (2006)
OPA + DFG
20 30 40 50 60 70 800
1
2
3
4
514 10 8 7 6 5 4
longueur d'onde [μm]
Ene
rgie
[μJ]
Fréquence [THz]
η=25%
J.M. Fraser, C. VentalonParametric cascade downconverter for intense ultrafast mid-IR generation beyond the Manley-Rowe limitAppl. Opt. 45, 4109 (2006).
IR generation through parametric cascade downconversion
Detection method linear with the electric field
ω/2π
1 M
Hz
10 M
Hz
100
MH
z
1 G
Hz
10 G
Hz
100
GH
z
1 TH
z
10 T
Hz
100
THz
1 PH
z
10 P
Hz
100
PHz
λ
100
cm
10 c
m
1 cm
100
mm
10 m
m
1 m
m
100
µm
10 µ
m
1 µm
100
nm
10 n
m
1 nm
Radio µ-waves IR Visible UV RX
R(ω)
)()()( tEtRtS ⊗= )()()( ωωω ERS =
Electro-opticdetection
Electro-optic detection
C. Kubler, R. Huber, S. Tubel, A. LeitenstorferUltrabroadband detection of multi-terahertz field transients with GaSe electro-optic sensors: Approaching the near infraredAppl. Phys. Lett. 85, 3360-3362 (2004)
)2(χ PBS+
-
• Second-order nonlinear autocorrelation• FROG : B. A. Richman et al., Opt. Lett. 22, 721 (1997) ; T. Witte et al., Opt. Lett. 27,131 (2002)• Pump-probe : S. Yeremenko et al., Opt. Lett. 27, 1171 (2002)• Time-domain HOT SPIDER : C. Ventalon et al., Opt. Lett. 28, 1826 (2003)• Chirped-Pulse Up-conversion : K. J. Kubarych et al., Opt. Lett. 30, 1228 (2005)
Measurements based on quadratic detectorsQuadratic and stationary detection results in a signal depending on |E(ω)|² only :Information on the spectral phase can be retrieved only using nonlinear optics !
-600 -400 -200 0 200 400 600012345678
inte
nsity
[A.U
.]
Delay [fs]
|ε(ω)|²
ω
IRω0
|ε(ω−ω0)|²
0ωω +IR0ω
Sum Frequency Mixing(SFM)
IRω
0ω0ωω +IR
Spectrometer CCD
Translation from IR to visible
Spectral domain of CCD cameras
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. JonasMid-infrared electric field characterization using a visible charge-coupled-device-based spectrometerOpt. Lett. 30, 1228-1230 (2005)
χ(2)
SpectrometerRegen Compressor
OPADFG
Translation from IR to visible
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. JonasMid-infrared electric field characterization using a visible charge-coupled-device-based spectrometerOpt. Lett. 30, 1228-1230 (2005)
IR ZAP SPIDER
χ(2)
SpectrometerRegen Compressor
OPADFG
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. JonasMid-infrared electric field characterization using a visible charge-coupled-device-based spectrometerOpt. Lett. 30, 1228-1230 (2005)
IR ZAP SPIDER
Indirect mid-IR pulse shaping
)()()()()( **SPSIRSPSPSSPPIR EddEEE ωωωωωδωωωωω −≈−−= ∫
H.-S. Tan, E. Schreiber, W.S. Warren, Opt. Lett. 27, 439 (2002)
S.-H. Shim, D. B. Strasfeld, E. C. Fulmer, M. T. ZanniFemtosecond pulse shaping directly in the mid-IR using acousto-optic modulationOpt. Lett. 31, 838-840 (2006)
Direct mid-IR pulse shaping
Conclusion
The reliability of mid-infrared femtosecond sources (5-20 µm) based on OPA is nowadays comparable to that of visible femtosecond sources.Efficiency remains limited due to small energy of infrared photons and to the use of two amplification stages. There is room for improvement through the use of new nonlinear materials or of primary laser sources directly in the near infrared (1-2µm).