Junji Kawanaka, Hwang Sungln, Koji Tsubakimoto, Kana Fujioka, Yasushi Fujimoto, and Noriaki Miyanaga

Institute of Laser Engineering (ILE), Osaka University

Ultra-Broadband Optical Parametric Chirped Pulse

Amplification with Partially Deuterated KDP Crystal

ILE / Osaka

HEC-DPSSL Lake Tahoe, California 11th September 2012

RAL: Astra Gemini

ILE Texas

Vulcan:10PW (300J, 30fs)

ILE, LFEX (10kJ, 1-10ps)

JAEA

UK

LLNL

OMEGA-EP: (2.6kJ, 10ps)

MPQ: (5J, 5fs)

LLNL:1PW (13J, 13fs) 10Hz

ILE/ENSTA 20PW (300J,15fs)

LLNL: NIF-ARC: (2.4-13kJ, 10ps) EU, ELI: 0.2EW

(3kJ,15fs), 10 beams CEA, PETAL: (3.5kJ, 0.5-5ps)

ILE-CREST: (150mJ, 5fs) 10Hz

RAL: Vulcan PW

10-4!

10-3!

10-2!

10-1!

100!

101!

102!

103!

10４!

Out

put e

nerg

y (J

)!

Pulse width (s)!10-15! 10-14! 10-13! 10-12! 10-11! 10-10!

1PW!

1TW!

1GW! 1MW!

1EW!

Gekko EXA

ILE, GEKKO EXA 0.2EW (2kJ,10fs)

OPCPA + Glass Amp.!OPCPA + Ti:Sapphire!All OPCPA!

Design!

Ultra-intense lasers over the world

✓ Sub-EW ✓ Few cycle

☀ Broadband amplification ☀ Temporal and spectral dispersion control

1. Arrayed-Beam Pumped OPA for kilo-joule

2. Partially Deuterated KDP 2-1 Broadband OPA Gain 2-2 Crystal Growth

3. Broadband Dielectric Grating

3-1 Groove Structure and Material

Outline

Arrayed Beam Pumped OPA for kilo-joule

Laser glass slab!46×81×4 cm3!

kJ-pump source based on LFEX-Laser technologies�

Large laser glass

m-size dielectric grating

2 x 2 disk amplifier

Arrayed compressor

Large-aperture OPCPA pumped by arrayed beams

OPCPA preamp.

35cmx35cm

30cm

KDP ω

ω

2ω

Pump Signal

λ = 1053 nm

λ = 527 nm

Nonlinear crystal

Proof-of-principle of OPA with random-phased pump

Pump laser

Nd:YLFoscillator

:

RPP

P1 P2

P3

Vacuum telescope

Telescope

DM PumpSignal, Idler

BBO

WP PL

WPGLP

EXP

AP

(a) 0 (b) ¹ /2 (c) ¹ (d) 3¹ /2 (e) 2 ¹

Phase

Signal

Pump

Idler

ランダム位相多ビーム励起

NFP

FFP

Pump

OPA

FFP

Random-phased pump

Virtually alignment free for beam combination ?

ランダム位相多ビーム励起

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 1.0 2.0 3.0 4.0 Diameter [Fλ]

RPP OPA

2-beam OPA

Before OPA

Nonlinear crystal�

Pump beams�

Signal�

Is 100PW feasible with single beam?!!→ Arrayed pumps in kJ are used.�

Large-aperture, ultra-broadband OPCPA with arrayed pumps

Partially Deuterated KDP (p-DKDP)

Sellmeier eqations of p-DKDP

p-DKDP Sellmeier equations by using KDP and DKDP,

(1) V. V. Lozhkarev, G. I. Freidman, V. N. Ginzburg, E. A. Khazanov, O. V. Palashov, A. M. Sergeev, and I. V. Yakovlev, “Study of broadband optical parameteric chirped pulse amplification in a DKDP crystal pumped by the second harmonic of a Nd:YLF laser,” Laser Phys. Vol. 15, No. 9 p.p. 1319-1333 (2005).

KDP and DKDP Sellmeier equations,

(2) Kevin W. Kirby and Larry G. DeShazer, “Refractive indices of 14 nonlinear crystal isomorphic to KH2PO4, JOSA B vol. 4, No. 7 pp.1072-1078 (1987).

(3) Frits Zernike, Jr., “Refractive indices of Ammonium Dihydrogen Phosphate and

Potassium Dihydrogen Phosphate between 2000 A and 1.5µ”, JOSA vol. 54, No. 10 pp. 1215-1220 (1964).

Temporal waveform in collinear OPCPA

θpm=36.9143 z

L=17mm

10 GW/cm2

20 W/cm2

DKDP (0.98)�

Δλ = 300 nm @1030nm CR = 1 nm/ps

1050 nm 850 nm 1250 nm

Non-gain-saturation

G = 300�

Seed

Seed

Amplified

Amplified

Gain Narrowing 300nm 110nm

Gaussian in temporal and spatial

Seed

Pump 515 nm

Seed

Pump

θpm=36.9143 @ 1030nm

z L=17mm

Seed

DKDP (0.98)�

CR = 1 nm/ps

Non-saturation condition

Temporal change of beam profile in collinear OPCPA

-100ps (930nm)

0ps (1030nm)

+100ps (1130nm)

x 1

7.5 x

1 15

Amplified

Seed

Pump

θpm=36.9143 θpm=36.9643

θs-p=0 z

L=17mm

Phase Matching

DKDP (0.98)�

CR = 1 nm/ps

Temporal change of beam profile in collinear OPCPA

Non-Phase Matching

x 1 15

x 1 15

x 1 7.5

x 1 15

0.05

-100ps (930nm)

0ps (1030nm)

+100ps (1130nm)

Gain bandwidth at off-phase-matching in collinear OPCPA

Phase Matching for λ0 and λ2ω

Non-Phase Matching for λ0 and λ2ω

Gain Narrowing 300nm 110nm

Gain Narrowing 300nm 50nm

-100ps

0ps +100ps

1 15

x 1

15 x

1 15

x 1

7.5 x

Gpeak = 300

Gpeak = 20

Deuteration dependence of gain bandwidth

10

11

12

13

14

15

16

100

105

110

115

120

125

130

135

140

145

150

0 20 40 60 80 100

FT-li

mite

d pu

lse

wid

th (n

s)�

Gai

n ba

ndw

idrt

h (F

WH

M) (

nm)�

Deuteration (%)�

Wavelength (nm)

Δk

(cm

-1)

145 nm�

10.5 fs �

0

0.02

0.04

0.06

0.08

0.1

0.12

0 20 40 60 80

100 120 140 160 180 200

0 0.1 0.2 0.3 0.4 0.5

Con

vers

ion

effic

ienc

y�

Gai

n ba

ndw

idrt

h (F

WH

M)

(nm

)�

Seed intensity (GW/cm2) �

Gain bandwidth broadening due to gain saturation

Pump beam depletion

Temporal profile (Spectral profile)

110 nm 190 nm 0.0% 10.1%

pDKDP(40%) + Gain Saturation in collinear OPCPA

Pump 10 GW/cm2

Signal 20 W/cm2

Seed

Seed

Amplified

Amplified

Signal 0.4 GW/cm2

Pump 10 GW/cm2

Amplified Signal

210 nm

pDKDP(40%)

DKDP(98%)

440 nm

Con. eff. 18.8%

How about Non-collinear ? pDKDP(40%) + Gain Saturation

Pump 150 GW/cm2 Signal 6 GW/cm2

pDKDP(40%)

465 nm

Seed Amplified

Con. eff. 18.8%

Con. eff. 8.0%

540 nm

Collinear

Non-Collinear

Seed

Amplified

1)  N-CL shows a broader gain bandwidth than CL. 2)  Need higher pump intensity in N-CL to recover

the reduced gain. 3)  Also, need to take much care of the optically

induced damage.

2010 Check the previous parameters in crystal growth Reconstruct the growth system 2011  Trial of crystal growth in cm-size with deuteration between 50% and 80% Storage procedure of the crystal 2012 Refractive index measurement (Sellmeier equations)

Growth Capping:7days Growth:33days　(2mm/day)

30mm

50mm

3-litter much mother solution to avoid segregation of dueterium

Crystal growth schedule of p-DKDP

20

30

40

50

60

70

80

90

0 20 40 60 80 100

30℃40℃50℃60℃70℃

溶解度　[g/100gH2O]

重水素化率 [%]

J. Crystal Growth, 53 (1981) 283.

Easier eduction For Tetragonal system

Deuterated ratio of mother solution ［%］

Natural temperature decrease without controlDifferent crystallization conditionC. Belouet et al. [7]

Basic Data of p-DKDP Crystal Growth

Dueteration ratio

Sol

ubili

ty (g

/100

H2O

)

Easier eduction For Orthorhombic system

Partially deuterated KDP crystal for broadband OPA

10cm

13% deuterated KDP Pumping Energy: 8.4 kJ Pulse width: 1 ns Beam size: 32 cm Energy fluence: 10 J/cm2

OPCPA output Energy: ~1.2 kJ Pulse width: 0.5 ns

13%! 50%! 60%!

70%! 80%!

Cracks due to unexpected rotator stopping during the growth process.

First production of p-DKDP crystal

Broadband Dielectric Grating

Groove structure

Λ : 0.7 µm (1429 grooves/mm) f : duty cycle (0.1~0.6) tg : groove depth (0.1 µm) θ : incident angle (65-80 degree)

Groove structure

Deflection Efficiency Map with Wavelength and Groove Depth

material：SiO2 f : 0.4 Θ : 73˚

Wavelength (µm)

Gro

ove

dept

h (µ

m)

Δλ = 300 nm @ R > 80%, tg = 0.4

Deflection Efficiency Map with Wavelength and Groove Depth

Material：HfO2 f : 0.4 θ : 65˚

Δλ = 400 nm @ R > 90%, tg = 0.3 Δλ = 500 nm @ R > 80%

Summary

We are starting the challenging basic technology researches for broadband amplification of OPCPA. 1. Arrayed beams pumped OPA for kilo-joule ・Random-phased pump OPA shows virtually alignment free for beam combination.

　 2. Partially deuterated DKDP ・Numerical calculation shows

(a)  Spectral gain bandwidth is reduced under non-gain-saturation (NGS) in collinear OPA.

(b)  Amplified beam profile looks axicon under NGS in collinear OPA. Also, gain bandwidth is further reduced.

(c) Non-collinear OPA expands the gain band width. (d) p-DKDP expands the gain bandwidth. (e) Gain saturation expands the gain bandwidth.

・Non-collinear OPA with p-DKDP(40%) under gain-saturation will realize Δλ = 540 nm, Eff. = 8%.

!3. Broadband grating ・FDTD calculation

!Δλ = 500 nm @ >80%, HfO2, tg=0.3, f=0.4, θ=65˚