Generation and characterization
of mid-infrared femtosecond pulses
C. Ventalon(1), K. J. Kubarych(2), J. M. Fraser(3), A. Bonvalet et M. Joffre
Laboratoire d’Optique et Biosciences
INSERM U451 – CNRS UMR 7645
Ecole Polytechnique – ENSTA
91128 Palaiseau cedex
http://www.lob.polytechnique.fr
(1)
(2)
(3)
Boston University
University of Michigan
Queen’s University
Motivations
Time-resolved infrared spectroscopy
Multidimensional spectroscopy
Vibrational coherent control
1. Generation of infrared femtosecond pulses
a) Optical rectification (inverse electro-optic effect)
P ( 2 ) (t ) = ε 0 χ ( 2 ) E (t ) E * (t )
ω
ω0
0 IR
b) Difference frequency mixing
P ( 2 ) (t ) = ε 0 χ ( 2 ) E2 (t ) E1* (t )
ω
0 IR
ω1
ω2
Infrared generation using optical rectification
Milieu
non-linéaire
Impulsion
visible de 12 fs
• Optical rectification :
P ( 2 ) (t ) = ε 0 χ ( 2 ) E0 (t )
2
P(t)
E0(t)
t
∂ 2 E n2 ∂ 2 E
∂ 2 P ( 2 ) (t )
• Propagation :
−
= μ0
∂t 2
∂z 2 c 2 ∂t 2
Impulsions infrarouges
nL ∂P ( 2)
E (t ) = −
2ε 0 c ∂t
A. Bonvalet et al., Appl. Phys. Lett., 67, 2907 (1995)
Infrared generation using optical rectification
Fréquence [THz]
50 40 30
20
1.5
Inténsité spectrale
Autocorrelation
2
1
0.5
0
-400 -200
0
200
Retard [fs]
400
4
8
12
16
Longueur d'onde [μm]
A. Bonvalet et al., Appl. Phys. Lett., 67, 2907 (1995)
Frequency mixing : one or two stages ?
1) One stage
λs = 1.6 to 0.97 µm
OPA
800 nm
λi = 1.6 to 4.5 µm
Simple but less efficient above 4.5 µm due to two-photon absorption
10 μm
5 μm
800 nm
400 nm
Transparency of nonlinear materials
KDP
BBO
LBO
YCOB
GCOB
KTA
KTP
RTA
KNBO3
LiNBO3
LiIO3
LiInS2
ZnGeP2
AgGaS2
AgGaSe
GaSe
Te
1
longueur d'onde [µm]
10
100
J. Non-crystalline solids 352, 2439 (2006)
Frequency mixing : one or two stages ?
1) One stage
λs = 1.6 to 0.97 µm
OPA
800 nm
λi = 1.6 to 4.5 µm
Simple but less efficient above 4.5 µm due to two-photon absorption
2) Two stages
λs = 1.6 to 1.2 µm
DFG
OPA
800 nm
λi = 1.6 to 2.4 µm
λIR=5 to 20 µm
OPA + DFG
10%
laser: Hurricane
Spectra Physics
100fs @ 800 nm
0.8 mJ
1 kHz
Energie [μJ]
5
2%
Sapphire
continuum
Pump :
1st stage
BBO
Signal + idler
longueur d'onde [μm]
14 10 8 7 6
5
4
Pump :
2nd stage
Phase matching
idler
calcite
Phase matching
4
3
η=25%
signal
2
IR
LWP filter
Delay τ
1
0
GaSe
20
30 40 50 60 70
Fréquence [THz]
80
Kaindl et al., JOSA B 17, 2086 (2000)
Ventalon et al., JOSA B 23, 332 (2006)
IR generation through parametric cascade downconversion
J.M. Fraser, C. Ventalon
Parametric cascade downconverter for intense ultrafast mid-IR generation beyond the Manley-Rowe limit
Appl. Opt. 45, 4109 (2006).
2. Characterization
Detection method linear with the electric field
S (ω ) = R(ω ) E (ω )
S (t ) = R(t ) ⊗ E (t )
Electro-optic
detection
R(ω)
Radio
µ-waves
IR
Visible UV RX
1 nm
100 PHz
10 nm
10 PHz
100 nm
1 µm
1 PHz
100 THz
10 µm
100 µm
10 THz
1 THz
1 mm
100 GHz
10 mm
10 GHz
100 mm
1 GHz
1 cm
10 cm
10 MHz
100 cm
1 MHz
λ
100 MHz
ω/2π
Electro-optic detection
χ ( 2)
+
PBS
-
C. Kubler, R. Huber, S. Tubel, A. Leitenstorfer
Ultrabroadband detection of multi-terahertz field transients with GaSe electro-optic sensors: Approaching the near infrared
Appl. Phys. Lett. 85, 3360-3362 (2004)
Measurements based on quadratic detectors
intensity [A.U.]
Quadratic 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 !
8
7
6
5
4
3
2
1
0
-600 -400 -200
0
200 400 600
Delay [fs]
• 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)
The problem of IR detection
|ε(ω)|²
Spectral domain of CCD cameras
ω
0
ωIR
Translation from IR to visible
|ε(ω)|²
Spectral domain of CCD cameras
|ε(ω−ω0)|²
ω
ω0
ωIR
0
ωIR
ω0
Sum Frequency Mixing
(SFM)
ωIR + ω0
ωIR + ω0
Spectrometer
CCD
Translation from IR to visible
Regen
Compressor
OPA
DFG
Spectrometer
χ(2)
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. Jonas
Mid-infrared electric field characterization using a visible charge-coupled-device-based spectrometer
Opt. Lett. 30, 1228-1230 (2005)
IR ZAP SPIDER
Regen
Compressor
OPA
DFG
Spectrometer
χ(2)
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. Jonas
Mid-infrared electric field characterization using a visible charge-coupled-device-based spectrometer
Opt. Lett. 30, 1228-1230 (2005)
IR ZAP SPIDER
K.J. Kubarych, M. Joffre, A. Moore, N. Belabas, D. M. Jonas
Mid-infrared electric field characterization using a visible charge-coupled-device-based spectrometer
Opt. Lett. 30, 1228-1230 (2005)
3. Mid-infrared pulse shaping
Indirect mid-IR pulse shaping
E IR (ω ) = ∫ E P (ωP ) ES* (ωS )dωP dωSδ (ωP − ωS − ωIR ) ≈ ES* (ωP − ωS )
H.-S. Tan, E. Schreiber, W.S. Warren, Opt. Lett. 27, 439 (2002)
Indirect mid-IR pulse shaping
H.-S. Tan, E. Schreiber, W.S. Warren, Opt. Lett. 27, 439 (2002)
Direct mid-IR pulse shaping
S.-H. Shim, D. B. Strasfeld, E. C. Fulmer, M. T. Zanni
Femtosecond pulse shaping directly in the mid-IR using acousto-optic modulation
Opt. Lett. 31, 838-840 (2006)
Conclusion
¾ The reliability of mid-infrared femtosecond sources (5-20 µm)
based on OPA is nowadays comparable to that of visible
femtosecond sources.
¾ 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).