Optical Parametric Oscillators (Optical Parametric Oscillators (OPOsOPOs) from the) from theContinuousContinuous--Wave to the Wave to the FemtosecondFemtosecond TimeTime--ScalesScales

MajidMajid EbrahimEbrahim--ZadehZadeh

ICFOICFO--InstitutInstitut de de CienciesCiencies FotoniquesFotoniques, 08034 Barcelona, , 08034 Barcelona, SpainSpainhttphttp://://www.icfo.eswww.icfo.es

t

Inte

nsity

το

Inte

nsity

t

OPO

NonlinearMaterial

Mirror Mirror

TunableLight

Pump

Wavelength (µm)

Dye

Ti3+:Al2O3(Ti:sapphire)

Cr3+:YAG

Cr2+:ZnSe

Co2+:MgF2

0.5 1.0 2.0 3.0

Tm3+:YAG

Cr3+:BeAl2O4(Alexandrite)

Cr3+:Mg2SiO4

1.80.4 0.6 0.80.7 0.9 1.41.2 1.6 2.2 2.4 2.82.6

Conventional Tunable Laser Sources Conventional Tunable Laser Sources

2E

1E

Ener

gy

Emission Spectrum

Ground States

Excited States

OPOsOPOs versus Tunable Lasersversus Tunable Lasers

Periodically poled LiNbO3 (PPLN) β-BaB2O4 (BBO)

LiB3O5 (LBO) OPOs

Wavelength (µm)

0.2 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Lasers

Dye

Cr2+:ZnSeTi:sapphire

Cr3+:YAG

Co2+:MgF2

Alexandrite

Cr3+:Mg2SiO4

Tm3+:YAG

_

+

)( E∆

Optical Parametric GenerationOptical Parametric Generation

_

+

Parametric Photons

phν

PumpPhotons

shν ihν(b)

etc.

etc.

Photon Picture

_

+

Parametric Waves

),( pp λν

),(33λν

StrongPump ),(

11λν

),(22λν

etc.

),(44λν

(a)

Wave Picture

Optical Parametric Generation: Frequency SelectionOptical Parametric Generation: Frequency Selection

[ ]Lrrvrrrr +χ+χ+χε= EEEEEEP .. (3)(2)(1)0 ....Nonlinear Dielectric:

)2(χ

ωp

ωsωi

isp ω+ω=ω

0isp ~kkkk −−=∆

ωp

ωi

ωs ωp

ωi

ωs

Generated Intensity

zcl20 cl4 cl6

),( pp λν

StrongPump

Parametric Amplification

Anisotropic Nonlinear Material

Phase-Match “Filter”

),( ss λν

),( ii λν

DepletedPump

coherence length

cl

Propagation Direction (z)

PhasePhase--MatchingMatching

Optical Parametric AmplificationOptical Parametric Amplification

( )( ) ]2/k[

]2/k[sinh1)0()()(G 222

2/1222222

s

ss

ll

lll

ll

∆−Γ

∆−ΓΓ+==ω

II

λλεπ

=Γ )0(8 pisisp0

2eff

22 I

nnncd

l

ΙpΙs

z

0

:0=−−= isp∆ kkkk

:0≠−−= isp∆ kkkk

)(cosh)(G 2s ll Γ=ω

22s 1)(G:)1~( GainLow ll l Γ+≅ω>Γ 2s e41)(G:)1( Gain High

)mW()10981()m( 2P822 /. I−− ×=Γ

)51m;2~~;Vpm3( ispiseff .~n~n~n/d µλλ=

)(coshG 2 ll Γ=

0isp ~kkkk −−=∆

Optical Parametric GainOptical Parametric Gain

Pulsed

CW Q-Switched Mode-locked Amplified

------ 10 mJ 15 nJ 10 µJ

------ 10 ns 100 fs 200 fs

5 W 1 MW 150 kW 50 MW

20 µm 1 mm 15 µm 15 µm

400 kW/cm2 30 MW/cm2 20 GW/cm2 7 TW/cm2

10 mm 10 mm 1 mm 1 mm

0.09 0.77 1.99 37

1.008 1.72 13.88 3.4 x 1031

τ p

P p

w p

Ip

l

Γl

G l

pE

Pump Laser Characteristics

SRO

Mirror Mirror

ωs (or ωi)

(a) DRO

Mirror Mirror

ωs

ωi

(b)

PE-SRO

Mirror Mirror

ωp

ωs (or ωi)

(c) TRO

Mirror Mirror

ωp

ωs

ωi

(d)

IC-SRO

Mirror Mirror

ωp

ωs (or ωi)ωp

ωp

Laser GainMaterial

(e)

OPOsOPOs: Resonance Configurations: Resonance Configurations

OPO DevicesOPO Devices

• Wavelength Versatility: Ultraviolet Mid-Infrared / THz

• Temporal Flexibility: CW Femtosecond

• Operation: > Room Temperature

• Practical Powers: 1 mW < P < 30 W

• Solid-State Design

• Stringent Material Requirements:

Optical Nonlinearity, Transparency, Phase- Matching, Damage Threshold,Mechanical and Chemical Stability

• Stringent Pump Laser Requirements:

High Spectral and Spatial Coherence, Sufficiently High Intensity

Wavelength (µm)0.2 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Periodically-poled LiNbO3 (PPLN)

KNbO3

KTiOPO4 (KTP), RbTiOAsO4 (RTA), KTiOAsO4 (KTA)

1

15

5

10

20

Periodically-poled KTiOPO4 (PPKTP), RbTiOAsO4 (PPRTA), KTiOAsO4 (PPKTA)

β-BaB2O4 (BBO)

Non

linea

r Stre

ngth

, def

f(p

m/V

)

Periodically-poled LiTaO3 (PPLT) : Demonstrated OPO Tuning Range

: Nominal Transparency

LiB3O5 (LBO)

New Nonlinear MaterialsNew Nonlinear Materials

HighHigh--Power CW OPO: PPLNPower CW OPO: PPLN

W. R. Bosenberg, A. Drobshoff, J. I. Alexander, L. E. Myers, and R. L. Byer, Opt. Lett. 21, 1336-1338 (1996).

T. J. Edwards, G. A. Turnbull, M. H. Dunn, M. Ebrahimzadeh, Appl. Phys. Lett. 72, 1527-1529 (1998).

HighHigh--Power IntraPower Intra--cavity OPO: KTAcavity OPO: KTA

Miniature CW IntraMiniature CW Intra--cavity OPO: PPLNcavity OPO: PPLN

D. J. M. Stothard, M. Ebrahimzadeh, and M. H. Dunn, Opt. Lett. 23, 1895-1897 (1998).

CW CW OPOsOPOs

Wavelength (µm)

CW

Out

put P

ower

(Wat

ts)

0.04

0.08

0.06

0.02

0.2 1.0 2.0 3.0 4.0 5.0 6.0

PPLN

0

5

0.1

1

LBO

PPLT

KTP

PPLN

KTA

PPLT

PPLN

PPRTA

KTP, PPKTP

MgO:LiNbO3

PPLN

0.6

0.8

3

4

2

0.2

0.4

LBO PPKTP

Pulsed Pulsed OPOsOPOs: Nanosecond : Nanosecond

Commercial System:

Tuning Range: 0.35-2.4 µm

M. Ebrahimzadeh, A. J. Henderson, and M. H. Dunn, IEEE J. Quantum Electron. 26, 1241-1252 (1990).

Out

put P

ulse

Ene

rgy

(10-

3Jo

ules

)

Wavelength (µm)

KNbO3

PPRTA

PPKTP

BBO

BBO

BBO

KTP

KTA

ZGP

PPKTP

BBO

50

1

5

10

100

200

PPLNLBO

LBO

PPLNLiNbO3+ AgGaSe2

BBO

0.2 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 11 12

Pulsed Pulsed OPOsOPOs: Nanosecond: Nanosecond

Ave

rage

Out

put P

ower

(Wat

ts)

Wavelength (µm)

PPRTA (1 kHz)BBO (30 Hz)

BBO (10 Hz, 30 Hz)

KTP (10 Hz)

KTA (10 kHz)

5.00.2 1.0 2.0 3.0 4.0 6.0 7.0 8.0

ZGP (10 kHz)

PPLT (1 kHz, 10 kHz)

PPLN (5-30 kHz)

PPLN (1 kHz)

PPLN (20 kHz)

PPRTA (20 kHz)

KTA (10 kHz)

PPLN (12.5 kHz)

5.0

0.1

0.5

1.0

10

20

0.2

0.3

0.4

0.6

0.7

0.8

0.9

2.0

3.0

4.0

Pulsed (Nanosecond) Pulsed (Nanosecond) OPOsOPOs: High: High--repetitionrepetition--raterate

Ave

rage

Out

put P

ower

(Wat

ts)

Spectral Coverage (µm)

LBO (1-2 ps, 100 MHz)

KTP (1 ps, 80 MHz)

KTP (12 ps, 75 MHz)

PPLN (4 ps, 120 MHz)

PPLN (8 ps, 2.5 GHz)

CTA (1 ps, 80 MHz)

0.2 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

LBO (15 ps, 75 MHz)

PPLN (4 ps, 120 MHz)

LBO (1-2 ps, 125 MHz)

PPLN (45 ps, 75 MHz)

PPRTA (1 ps, 80 MHz) LBO (1-2 ps, 80 MHz) PPLN (0.5 ps, 322 MHz)

PPLN (1 ps, 75 MHz)AgGaS2 (50-80 ps, 75 MHz)

AgGaS2 (50-80 ps, 75 MHz)

PPLN (50 ps, 75 MHz)

KTA (1-3 ps, 80 MHz)

LBO (1 ps, 80 MHz)

KTP (1-2 ps, 125 MHz)

LBO (22 ps, 75 MHz)

LBO (22 ps, 75 MHz)

KTA (7 ps, 83 MHz)

1.0

0.02

0.1

0.5

5.0

10.0

20.0

0

PicosecondPicosecond OPOsOPOs

Ave

rage

Out

put P

ower

(Wat

ts)

Spectral Coverage (µm)

KTP (75 fs, 90 MHz)

0.2 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

PPLN (150 fs, 84 MHz)

PPLN (60 fs, 81 MHz)

AgGaSe2 (230 fs, 82 MHz)BBO (13 fs, 80 MHz)

KNB (60 fs, 75 MHz)

LBO (40 fs, 80 MHz)

PPRTA (115 fs, 84 MHz)

KTP (62 fs, 76 MHz)

RTA (58 fs, 80 MHz)

KTA (85 fs, 100 MHz)PPLN (140 fs, 85 MHz)

CTA (56 fs, 75 MHz)

KTP (175 fs, 76 MHz)

0.9

0.02

0.1

0.5

0.8

0.7

0.6

0.4

0.3

0.2

0.08

0.06

0.04

0

FemtosecondFemtosecond OPOsOPOs

SummarySummary

Optical Parametric OscillatorsOptical Parametric Oscillators

Flexible solidFlexible solid--state sources of light with uniquestate sources of light with unique

spectral and temporal versatility spectral and temporal versatility

CW 13 fs1 Hz 1 GHz1 mW 30 W1 µJ 200 mJ400 nm 12 µm