requirements

AdvLIGO – optical layout

front end powerstages

modecleaner

pre-mode

cleaner

referencecavity

long baselinecavities

20W 200W

170W

frequency stabilization

power stabilizaiton

AdvLIGO PSL – subsystem layout

Advanced LIGO PSL – requirements

Power / Beamprofile: – 165W in gausian TEM00 mode– less than 5W in non- TEM00 modes

Drift: – 1% power drift over 24hr. – 2% pointing drift

Control:– tidal frequency acuator +/- 50 MHz, time constant <

30min – power actuator 10kHz BW, +/-1% range– frequency actuatot BW:<20o lag at 100kHz, range:

DC-1Hz: 1MHz, 1Hz-100kHz: 10kHz

frequency noise requirement

intensity noise requirement

further PSL requirements

• interfaces to detector control software • interfaces to DAQ system• environmental requirements: size, power,

cooling• reliability to meet detector duty cycle goal • easy to maintain (change of items with

lifetimes < 2years)

concept

PSL optical layout

NPRO1W

GEO typring laser

15W

high power

ring laser

200W

spatial filterresonator

(PMC)

AOMfrequencyreferenceresonator

Advanced LIGO Laser Design

f

f2f

QR

f

f

HR@1064HT@808

YAG / Nd:YAG / YAG3x 7x40x7

f QR f

FIEOM

NPRO

20 W Master

BP

High Power Slave

FI

modemaching optics

YAG / Nd:YAG3x2x6

BP

output

PSL – stabilization scheme

frequency stabilizationinner loop

frequency stabilizationouter loop

intensity stabilizationouter loop

intensity stabilizationinner loop

PMC loop

injection locking

frequencycontoller

NPRO

pre-modecleaner

reference cavity

temp PZT

EO

phaseshifter

mixer

AO

EO

to suspended mode cleaner

length controll

poweramplifier

intensity controller

pre-stabilized -LIGO 10W laser

LIGOI reference cavity, AOM, tidal correction

fused silica spacer

M3

PZT

M1

M2

• 713 MHz free spectral range• linewidth: 162 kHz in s-pol. , 3.2 MHz in p-pol.• circulating power 0.135MW/cm2 (for p-pol.), 2.64MW/cm2 (for s-pol.)• linewidth required to filter RIN(@25MHz) of 180W laser: 3.7MHz

pre-modecleaner

status

PSL set-up

NPRO1W

GEO typring laser

15W

high power

ring laser

200W

spatial filterresonator

(PMC)

AOMfrequencyreferenceresonator

Nd:YAG Master-Laser

NPRO (non-planar ring oscillator) by Innolight*

• output power: 800mW

• frequency noise: [ 10kHz/f ] Hz/sqrt(Hz)

• power noise: 10-6 /sqrt(Hz)

* US dristibution: Resonant optics Corp., San Martin CA

High Power Locking SchemeMaster

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p sf f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

• 2W Miser

Mephisto 2000 Innolight

• EOM: New Focus

@ 29,02 MHz

• Isolator: Gsänger

GEO 600 Slave Laser

performance of the LIGOI frequency stab

High Power Locking SchemeMedium Stage

• 12 W med. power stage

based on GEO 600 laser

design

opt ~ 30 %

• Isolator: Gsänger

high power design

GEO 600 Slave Laser Prototype IIFrequency Stability

1 10 100 1000 10000 10000010

-1

100

101

102

103

104

105

106

quasi monolithic slave relative to stabilized NPRO (inj.-lock actuator signal)

discrete component slave (ditto) free running NPRO

relative to a reference cavity

Fre

que

ncy

Flu

ctua

tions

[H

z/H

z1/2 ]

Frequency [Hz]

12W injection-locked laser-system

• NPRO (non-planar ring oscillator) master laser, output power: 800mW

• slave laser optical components mounted on rigid resonator-spacer (Invar)

• 12W output power (< 5% in higher TEM modes)

• injection-locking stable over days

High Power Slave

• 87 W output power• linear polarized• single transverse mode

• M2x,y ~ 1,2

Input beam( M aster )

O utput beam

BP

H W P

Q R

30% O C

PZM

Experimental/Diode Temperature Control

L a s e r -D io d e

P T 1 0 0 0

A/

D C

ha

ng

er

D/A

Ch

an

ge

r

P e lt ie rA m p lif ie r

P e l ti e rH e a t S in kL ig h t B u s

P C

d igit a lP ID -C o n t ro lle r

P h o t o -D io d e

P T 1 0 0H a rd w a re

In te r lo c k

P o w e r

S u p p ly

temperature resolution: 0.01K

temperature fluctuations: 2-3 digits

temperature stability better than 0.05K

laser diode JENOPTIK 30 W, fiber coupled, NA 0.22; 800 m

Experimental/Diode Box

•4 boxes

• each 10 X 30 W fiber-coupled diodes

1200 W pump Power

upcoming:

• 40 diode power measurements

laser power control for

each diode

laser diode (10)

ADC/DAC

peltier driversovertemp interlocks

heat sink (2)

user interface4 systems (boxes)

40 temperatures

4 current controls (1 per box)

High Power Locking Scheme

• 87 W high power slave

single transverse mode

M2 ~ 1,2

opt ~ 23 %

High Power Locking Scheme

M ISEREO M FI

M odem aching

PD

FI

O utputbeam

PD PD

PM C

C C D

PD

Results

First high power injection locked laser system

87 W linear polarized, single frequency,

single transverse mode

( total power of all systems ~ 101 W )

total optical efficiency 22%

locking direct to 2 W master possible

single frequency output power ~ 70 W

Beam Characterization

2,00E+008 3,00E+008 4,00E+008 5,00E+008 6,00E+008 7,00E+008 8,00E+0080,000000

0,000005

0,000010

0,000015Res.Bandwith 50 KHz

PD

Sig

nal [

V]

f [Hz]

Beat signals of free running slave

no higher order modes detect

Beam profile of locked system

M2~1.1 , less elliptical beam

Relock Time

-0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4-8

-7

-6

-5

-4

-3

-2

-1

0

1

2Piezo Ramp:Master 1,3 Hz (770ms)Slave 2.5 Hz (400ms)

PD

Sig

na

l [V

]

t [s]

Slave 12 W Master

relock time < 500 ms

faster relock possible depending on piezo ramp

System Optimization

To get full injection locked power following things

has to be optimized:

• Modemaching in the high power slave

( FI with compensated thermal lens )

• Outputcoupler of high power slave

•optimize gain overlap of different Lasers

• implement pumplight optimization

next steps

Pump Conceptsmode selective pumping

0 20 40 60 80 100

500

1000

1500

2000

2500

3000

3500

4000

4500

W/c

m2

x

w = 1mm

2 4 6 8 10

2

4

6

8

10

X

Y

2 4 6 8 10

2

4

6

8

10

X

Y

Laser Rod

Objektiv

Glas Rod

10 x 30 W

Pump Light Homogenization

20 40 60 80 100 120 140 160 180 2000

10

20

30

40

50

60

mu

limo

de

ou

tpu

t po

we

r [W

]

Pump Power [W]

with Homogenization w/o Homogenization

30 % more output

power with

homogenization

better gain overlap

and less distortion

for low order modes

New Head Design

Pump Chamber

2.5 cmwater flow

Birefringence compensation

Find working point with less birefringence

Pump Light Homogenization

fluorescence w/o

homogenization

fiber bundle FS- rodoptics

laser crysta l

Homogenization of Pump Light

2 4 6 8 10

2

4

6

8

10

2 4 6 8 10

2

4

6

8

10

Glas Rod 3x30mm

2 4 6 8 10

2

4

6

8

10

X

Y

2 4 6 8 10

2

4

6

8

10

X

Y

simulation

10 x 800 µm

measured

30 x 800 µm

0 20 40 60 80 100

2000

3000

4000

5000

6000

7000

8000

9000

W/c

m2

x

Pump Conceptsmode selective pumping

w = 2 mm

2 4 6 8 10

2

4

6

8

10

X

Y

2 4 6 8 10

2

4

6

8

10

X

Y

Laser Rod

Objektiv

Glas Rod

10 x 30 W

Optimization of Pump Light Distribution

CCD

• alignment of homogenous and centered pump light profile• pump power calibration for PD-readout

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p sf f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

• Test different laser rods 4,5 mm• Test different pump spot sizes

find best laser design before doubling the system

Optimize Resonator

Advanced Ligo Laser 1st. Step

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p sf f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

f f2 fQ Rf f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

• Optimized laser head with respect to

beam quality and output power• up to now 100 W of output power in

single transverse mode are demonstrated

Advanced Ligo Laser 2st. Step

f

f2 f

Q R

f

f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0

f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p sf

f2 f

Q R

f

f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

f

f2 f

Q R

f

f

B r e w s t e r P l a t e

H R2 0 % O C

8 0 1 5 0 5 0f i b e r b u n d l e1 0 X 3 0 W r e l a y o p t i c s 5 4 m m l a s e r r o d w i t h t w o u n d o p e d e n d c a p s

f

f2f

QR

f

f

HR@1064

HT@808

f QR f

BP

output

from Master

Modeling/Overview

pump light distribution

•ray tracing

•analytical approximation

•experimental data

Finite Element Method for

calculating

•temperature distribution

•mechanical stress

•deformation

wave propagation through

inhomogenous medium

•finite differencing•split step fourier approach

calculation of optical

properties

•thermal lens

•stress-induced birefringence

heat generation

coolinggain

k-vector

Model

assumption:

cylinder symmetrical pump light distribution

•model takes into account temperature dependent properties wavelength dependent absorption coefficient

temperature dependent heat conducitvity

temperature dependent expansion coefficient

temperature dependent dn/dT

3 m m diam eter54 m m length

Fox/Li ApproachIterative Solution of Kirchhoff integral equations

•inhomogenous distributed gain,

refractive index, birefringence

concentrated in gain/phase sheets

•propagation between gain/phase

sheets and in free space described

by FFT propagator

initial distributed E(x,y,z0)

(e. g. noise)

convergence ?

output power

beam quality

yesno

medium

free propagation

mirror/aperture

free propagation

medium

mirror/aperture

free Propagation

free Propagation

Abberations/End Pumped vs. Transversally Pumped

-0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6-0,10

-0,05

0,00

0,05

0,10

0,15

OPD, deviation from ideal lens O

PD

-OP

Did

eal[

m]

r [mm]

-0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6-0,10

-0,05

0,00

0,05

0,10

0,15

OPD, deviation from ideal lens O

PD

-OP

Did

eal[

m]

r [mm]

-0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6-0,10

-0,05

0,00

0,05

0,10

0,15

End Pumped Transversally Pumped

OPD, deviation from ideal lens O

PD

-OP

Did

eal[

m]

r [mm]

<10 nm

Thermal Modeling/Temperature Distribution

varying with pump spot diameter (pump power kept constant)

500 m

Thermal Modeling/Maximum Temperature

0 1000 2000 3000 4000 5000

80

90

100

110

120

130

140

Maximum Temperature vs. Pump Spot Radius m

axim

um t

empe

ratu

re [

°C]

pump spot radius [m]

Von Mises Stress

varying with pump spot diameter (pump power kept constant)

500 m

Mechanical Stress/Von Mises Equivalent Stress

varying with pump spot diameter (pump power kept constant)

0 1000 2000 3000 4000 5000

40

50

60

70

80

90

100

110

120

130

140

150 Maximum Equivalent Stress vs. Pump Spot Radius

max

imum

eq

uiva

lent

str

ess

[MP

a]

pump spot radius [m]

Resumé

•100 W of output power will be achieveable•abberations will have to be compensated for•abberations are comparable in end pumped and transversally pumped rod

•Modeling

•Experimental

•4 diode boxes have been set up (1200 W of pump power)•temperature stabilization works•pump light homogenization has been demonstrated•45 W single mode and 75 W multi mode laser has been demonstrated (single rod, no compensation)

alt. concept

Face-pumping vs Edge-pumping

Pumping

Cooling

zig-zagplane

Pumping

Cooling

zig-zagplaneFace-

pumping

Edge-pumping

zig-zag slab

Experimental Setup for 100W demonstration

ISOLA

TOR

Mode-matching

optics 20 W

Amplifier

Lightwave Electronics

Mode-matching

optics

Edge Pumped Slab #1

Output Power = 32 W

End Pumped Slab

Pump Power = 420 W

Output Power = 65 W

Mode-matching

optics

Edge Pumped Slab #2

Pump Power = 300 W

Output Power = 110 W

Mode-matching

optics

10W LIGO

MOPA

System

10W LIGO Laser

400mW

NPRO

10W

Amplifier

Characteristics:

• Single frequency.

• TEM00

• Narrow linewidth.

• Low frequency & amplitude noise.

Nd:YAG Laser Head

3.8 cm

808nm Pump

0.6% Nd:YAG

undoped end

undoped end

808nm Pump

signal IN

signal OUT

1.51cm

3.33cm

1.51cm

End pumped slab geometry

Motivation -> Higher efficiency

• Near total absorption of pump light.

• Confinement of pump radiation leads to better mode overlap

1.1mm X 0.9mm

Edge Pumped Slab #1

Output Power = 35 W

Mode-matching

optics

ISOLA

TOR

Mode-matching

optics 20 W

Amplifier

Lightwave Electronics

Mode-matching

optics

10W LIGO

MOPA

System

What next for the 100W experiment?

2-pass End Pumped Slab

Pump Power = 230 W

Expected Output Power = 100W

Key: Improve absorption of pump

light and achieve

the expected small signal gain.

Pump Power = 130 Output TEM00Power = 50 W

ISOLA

TOR

Mode-matching

optics 20 W

Amplifier

Lightwave Electronics2-pass End Pumped

Slab #1

Mode-matching

optics

10W LIGO

MOPA

System

Scaling to 200 W : Experimental Plan

2-pass End Pumped Slab #2

Pump Power = 430 W

Expected TEM00

Output Power = 160W

TO PRE MODE

CLEANER

WBS plan

manpowercosting

Laser Zentrum Hannover

Max-Planck InstitutUniversity of GlasgowUniversity of Hannover

GEO600 pre-stabilized laser

High-power solid- state-lasers design

power and frequency stabilization

LIGOII pre-stabilized laser

LIGO LabStanford

Adelaide

the LIGOII laser-team

German proposal