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

J. Non-crystalline solids 352, 2439 (2006)

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

2. Characterization

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

Spectral domain of CCD cameras

The problem of IR detection

|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

3. Mid-infrared pulse shaping

Indirect mid-IR pulse shaping

)()()()()( **SPSIRSPSPSSPPIR EddEEE ωωωωωδωωωωω −≈−−= ∫

H.-S. Tan, E. Schreiber, W.S. Warren, Opt. Lett. 27, 439 (2002)

H.-S. Tan, E. Schreiber, W.S. Warren, Opt. Lett. 27, 439 (2002)

Indirect mid-IR pulse shaping

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).