Harald LückHarald Lückfor the GEO teamfor the GEO team

ILIAS Meeting

Palma, October 2005

What is GEO-HF ?What is GEO-HF ?

A research and upgrade programA research and upgrade program instead of the instead of the name of a new detector name of a new detector

sequential upgradessequential upgrades of GEO600 (similar to of GEO600 (similar to LIGO+ / VIRGO+ )LIGO+ / VIRGO+ )

prototype researchprototype research to prepare these upgrades to prepare these upgrades support transit of support transit of 3rd generation3rd generation Lab research to Lab research to

detector subsystems or detector configuration detector subsystems or detector configuration

12W Laser

modecleaner

interferometer with „dual recycling“

detector

Optical LayoutOptical Layout

101

102

103

10-24

10-23

10-22

10-21

10-20

10-19

10-18

Freq. [Hz]

ASD

[h/

Hz]

GEO600 Theoretical Noise Budget

v2.0

SeismicSuspension TNSubstrate TNCoating TNThermorefractiveShot 200HzTotal

GEO600 Noise Sources GEO600 Noise Sources (Design values)(Design values)

101

102

103

10-24

10-23

10-22

10-21

10-20

10-19

10-18

Freq. [Hz]

ASD

[h/

Hz]

GEO600 Theoretical Noise Budget

v2.0

SeismicSuspension TNSubstrate TNCoating TNThermorefractiveShot 1 kHzTotal

GEO600 Noise Sources GEO600 Noise Sources (Design values)(Design values)

GEO HF - MotivationGEO HF - Motivation Provide scientifically interesting data with the GEO Provide scientifically interesting data with the GEO

instrument until 2014instrument until 2014– optimized at low frequencies for network analysis oroptimized at low frequencies for network analysis or– optimized for high frequency sources optimized for high frequency sources

Perform developments and tests towards third Perform developments and tests towards third generation detectors generation detectors – technologies, materials and optical schemes technologies, materials and optical schemes

Maintain capability to do high-fidelity Maintain capability to do high-fidelity measurementsmeasurements– Discover and analyze additional noise sources Discover and analyze additional noise sources – keep team of experts in GEO collaborationkeep team of experts in GEO collaboration

→ upgrade GEO600 and work on prototypes

Shot NoiseShot Noise

101

102

103

10-24

10-23

10-22

10-21

10-20

10-19

10-18

Freq. [Hz]

ASD

[h/

Hz]

GEO Theoretical Noise Budget

SeismicCoating TNThermorefractiveShot 1 kHzShot 200HzShot 500Hz

High Frequency SourcesHigh Frequency Sources

Possible way forward for Possible way forward for ‘GEO-HF’‘GEO-HF’

101

102

103

10-24

10-23

10-22

Freq. [Hz]

ASD

[h/

Hz]

GEO Theoretical Noise Budget

SeismicCoating TNThermorefractiveShot 1 kHz

improvements without improvements without changing mirrorschanging mirrors– increase circulating powerincrease circulating power– improve thermal improve thermal

compensation schemecompensation scheme– optimize signal recycling optimize signal recycling

bandwidthbandwidth use squeezed light to use squeezed light to

reduce shot noisereduce shot noise change main mirrorschange main mirrors

– reduce coating thermal reduce coating thermal noise if possiblenoise if possible

– further increase circulating further increase circulating power and / or reduce power and / or reduce signal recycling bandwidthsignal recycling bandwidth

Laser

modecleaner

interferometer with „dual recycling“

detector

ChangesChanges

increase laser power

40W / 200W

Nd:YAG 200W Laser SystemNd:YAG 200W Laser System

0.8W12W

200W

Injection-Locked Single Frequency PowerInjection-Locked Single Frequency Power

P = 195 W

continuous single-frequency

operation >8h

00:00 00:10 00:20 00:30 00:400

50

100

150

200

Ou

tpu

t P

ow

er

[W]

Time [hh:mm]

400 500 600 700 800 900 1000 1100 12000

50

100

150

200

250

300

Slope: 30 %

Out

put P

ower

[W]

Pump Power [W]

930 940 950 960 970205

210

215

220

225

230

213 W; M2 =1,14

215 W; M2 =1,2

218 W; M2 =1,3

225 W; M2 =1,45

Out

put P

ower

[W]

Pump Power [W]

4 Rod Nd:YVO4 Rod Nd:YVO44

AmplifierAmplifier39W output power11W seed / 115W pump

GEO 600 style

11W seed laser

2/8/2 mm Nd:YVO4 rod

Laser

modecleaner

interferometer with „dual recycling“

detector

ChangesChanges

reduce Finesse of MC to keep peak intensity

constant

•mid-arm pumping

•new gate valves

Laser

modecleaner

interferometer with „dual recycling“

detector

ChangesChanges

•(reduce absorption)

•thermal compensation

Faraday Rotator

Squeezed state

Squeezed lightSqueezed light

Signal-recycling mirror

Power-Recycling mirror

Laser

Photo diode

600 m

600 m

Rotated Squeezing EllipseRotated Squeezing Ellipse

Table Top SetupTable Top Setup

Sqeezing Enhanced Sqeezing Enhanced Signal/Noise Signal/Noise

Laser

modecleaner

interferometer with „dual recycling“

detector

Optional ChangesOptional Changes

replace main mirrors

Further GEO-HF Further GEO-HF optional changesoptional changes

based on thermal noise based on thermal noise considerations we consider considerations we consider replacing the end mirrors with replacing the end mirrors with new mirrorsnew mirrors

better coatingsbetter coatings (mechanical and (mechanical and optical losses) if availableoptical losses) if available

possibly switch to possibly switch to silicon/ silicon/ sapphiresapphire if thermal noise if thermal noise performance is better than in performance is better than in fused silicafused silica

Coated fused silica mirror for GEO600

~18cm diameter

Thermal Noise for GEO Main Thermal Noise for GEO Main OpticsOptics

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [H

z-1/2

]

GEO-HF noise levels based on best possible coating losses

full coating, silicadoped coating, silicaaperiodic coating, silicasilica substratethermorefractive BS

Ongoing lab work on Ongoing lab work on coatingscoatings

Considerable work in LIGO Scientific Collaboration Considerable work in LIGO Scientific Collaboration and elsewhere on studies of coating lossand elsewhere on studies of coating loss

Results suggest:Results suggest:– TaTa22OO55 is dominant source of coating dissipation is dominant source of coating dissipation – doping Tadoping Ta22OO55 with TiO with TiO2 2 can reduce dissipation by ~factor 2can reduce dissipation by ~factor 2

Further, studies by Pinto et al suggest by using multi-Further, studies by Pinto et al suggest by using multi-layers of ‘non-standard’ periodicity fraction of lossy layers of ‘non-standard’ periodicity fraction of lossy high index material may be reduced?high index material may be reduced?

SiliconSilicon

Strong interest in cryogenic silicon for use in ‘3Strong interest in cryogenic silicon for use in ‘3 rdrd generation detectors’generation detectors’

Laboratory studies ongoing on:

fabrication of, and dissipation in, silicon suspension elements

intrinsic dissipation in bulk silicon

fabrication and dissipation of monolithic silicon pendulums

e.g. GEO-HF, EGO

Silicon suspension technology.

future detectors

Thermal noise optionsThermal noise options

101

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [H

z-1/2

]

full coating, silicadoped coating, silicaaperiodic coating, silicasilica substrateaperiodic coating, sapphiresapphire substrateaperiodic coating, siliconsilicon substrate

Prototype Work within Prototype Work within GEO-HFGEO-HF

Glasgow Glasgow (in operation):(in operation): – Advanced Configuration PrototypeAdvanced Configuration Prototype– Cryogenic Materials Test SystemCryogenic Materials Test System

Hannover Hannover (planned):(planned):– test subsystem before installation in GEOtest subsystem before installation in GEO

active seismic isolation system active seismic isolation system digital control digital control fast mirror installation tools and techniquesfast mirror installation tools and techniques

– test 3rd Generation techniques and configurationstest 3rd Generation techniques and configurations

GEO-HF SummaryGEO-HF Summary

We plan to We plan to operate a flexible GW detectoroperate a flexible GW detector in a worldwide in a worldwide network until advanced IFOs come online.network until advanced IFOs come online.

Sequential upgradesSequential upgrades to improve high frequency sensitivity to improve high frequency sensitivity will be made.will be made.– higher circulating powerhigher circulating power– lower coating thermal noise ( ? )lower coating thermal noise ( ? )– squeezed light injectionsqueezed light injection

GEO collaboration will GEO collaboration will operate prototypesoperate prototypes to prepare to prepare these upgrades and these upgrades and

to support the transit of to support the transit of 3rd generation3rd generation Lab research to the Lab research to the detector subsystems or detector configuration level.detector subsystems or detector configuration level.

Timeline: starting upgrading after extended data taking Timeline: starting upgrading after extended data taking 2007/20082007/2008

Proposal for ~3.5 M€ approved by MPGProposal for ~3.5 M€ approved by MPG

0.0E+00

2.0E-08

4.0E-08

6.0E-08

8.0E-08

1.0E-07

1.2E-07

1.4E-07

30 35 40 45 50 55 60

Frequency (kHz)

Lo

ss

[111]

[100]

Results for silicon at room temperatureResults for silicon at room temperature

Lowest loss obtained so far = Lowest loss obtained so far = (9.6 +/- 0.3) x 10-9

Comparable with the lowest loss factors measured at room Comparable with the lowest loss factors measured at room temperaturetemperature(consistent with results by Mitrofanov et al from earlier times)(consistent with results by Mitrofanov et al from earlier times)

(Cryogenic measurements in preparation)(Cryogenic measurements in preparation)

The doped [111] sample typically showed lower dissipation, though whether this was due to the crystalline orientation of the sample, the dopant, or some other reason, is as yet unknown.

Measured loss factors for two samples of bulk silicon

Bandwidth Finesse of the SR cavity Reflektivity of MSR

Signalrecycling-Etalon (r=150mm, d=75mm)

Reflectivity is controlled by temperature

Controlling the SR bandwidthControlling the SR bandwidth

Heater

Diffraction GratingsDiffraction Gratings

1st order Littrow

2nd order Littrow

All-Reflected CavitiesAll-Reflected Cavities

University of Jena

Littrow order 1st 2nd

Finesse 15801580 400400

diff. efficiency 99.62%99.62% 0.58%0.58%

loss 0.2%0.2% 0.4%0.4%

Title: The GEO-HF Project Title: The GEO-HF Project

Abstract: The GEO 600 gravitational wave detector uses advanced Abstract: The GEO 600 gravitational wave detector uses advanced technologies like signal recycling and monolithic fused-silica suspensions to technologies like signal recycling and monolithic fused-silica suspensions to achieve a sensitivity close to the km scale LIGO and VIRGO detectors. As achieve a sensitivity close to the km scale LIGO and VIRGO detectors. As soon as the design sensitivity of GEO600 is reached the detector will be soon as the design sensitivity of GEO600 is reached the detector will be operated as part of the worldwide network to acquire data of scientific interest. operated as part of the worldwide network to acquire data of scientific interest. The limited infrastructure at the GEO site does not allow for a major upgrade of The limited infrastructure at the GEO site does not allow for a major upgrade of the detector. Hence the GEO collaboration decided to improve the sensitivity of the detector. Hence the GEO collaboration decided to improve the sensitivity of the GEO detector by small sequential upgrades some of which will be tested in the GEO detector by small sequential upgrades some of which will be tested in prototypes first. The development, test and installation of these upgrades are prototypes first. The development, test and installation of these upgrades are named "The GEO-HF Project" and this contribution will give a status report on named "The GEO-HF Project" and this contribution will give a status report on this project. this project.

contentscontents GEO600GEO600

– descriptiondescription– current sensitivitycurrent sensitivity– limitslimits

GEO HF DetectorGEO HF Detector– motivationmotivation– sourcessources– ways forwardways forward

increase circulating power and power handling capabilityincrease circulating power and power handling capability change optics if coating technology allows for lower coating thermal noisechange optics if coating technology allows for lower coating thermal noise use squeezed lightuse squeezed light

GEO HF PrototypesGEO HF Prototypes– test subsystems / optical layout before installation test subsystems / optical layout before installation – test installation procedures for fast installation at site test installation procedures for fast installation at site – allow for high displacement sensitive measurements allow for high displacement sensitive measurements – test and develop third generation materials, optical readout schemes, control test and develop third generation materials, optical readout schemes, control

schemesschemes

Improvements to GEO Improvements to GEO sensitivity possible by sensitivity possible by

changing to silicon mirrors? – changing to silicon mirrors? – possible option.possible option.

101

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [/

Hz]

substrate, fp, cavities silicon, silica bscavitiesbsdoped coating, totalcoating, cavitiescoating, bstotal (fp substrate + fp coating)thermorefractive

Improvements to GEO Improvements to GEO sensitivity possible by sensitivity possible by

changing to silicon mirrors? – changing to silicon mirrors? – possible option.possible option.

101

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [/

Hz]

substrate, fp, cavities silicon, silica bscavitiesbsdoped coating, totalcoating, cavitiescoating, bstotal (fp substrate + fp coating)

102

103

104

10-24

10-23

10-22

10-21

Frequency [Hz]

h [H

z-1/2

]GEO-HF noise levels based on best possible coating losses

full coating, silicadoped coating, silicaaperiodic coating, silicasilica substrateaperiodic coating, sapphiresapphire substrateaperiodic coating, siliconsilicon substrate

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [H

z-1/2

]GEO-HF noise levels based on best possible coating losses

full coating, silicadoped coating, silicaaperiodic coating, silicasilica substrateaperiodic coating, sapphiresapphire substrateaperiodic coating, siliconsilicon substrate

Current estimate of thermal Current estimate of thermal noise limited sensitivity of noise limited sensitivity of

GEO GEO

Uses:Uses:– Substrate loss of 1 x 10Substrate loss of 1 x 10-7 -7 (Suprasil mirrors)(Suprasil mirrors)– Current SiOCurrent SiO22/Ta/Ta22OO55 coatings coatings

101

102

103

10410

-24

10-23

10-22

10-21

Frequency [Hz]

h [

/H

z]substrate, loss = 1e-7standard coatingTotal (coating + substrate)

Phase squeezing

Squeezing at 45°

Phase squeezing

Amplitude squeezing

Phase squeezing

Squeezing at 45° Squeezing at -45°

Amplitude squeezing

Phase squeezing

Squeezing at 45°

Frequency dependent

squeezing, (single filter cavity)

Squeezing vs Squeezing vs QuadratureQuadrature

R. Schnabel et al., Class. Quantum Grav. 21, S1045 (2004)]

101

102

103

10410

-24

10-23

10-22

10-21

Frequency [Hz]

h [

/H

z]substrate, loss =1e-7substrate, loss =5e-9

Assume: Assume: – Loss in Suprasil = 5 x 10Loss in Suprasil = 5 x 10-9-9

In this case we would then be limited by coating thermal noise In this case we would then be limited by coating thermal noise strong interest in strong interest in reducing coating dissipationreducing coating dissipation

Limit set by coating thermal noise alone

Estimated GEO600 thermal Estimated GEO600 thermal noise – high Q valuenoise – high Q value

Possible improvements to Possible improvements to thermal noise limited thermal noise limited

sensitivity of GEO for better sensitivity of GEO for better coatingscoatings

101

102

103

10410

-24

10-23

10-22

10-21

Frequency [Hz]

h [

/H

z]

substrate, loss = 5e-9

Standard coating+substrateCoating using doped Ta2O5

Doped coating+substrateReduced coating noise using Non-Standard Periodicity (NSP) ?????– Pinto et alNSP coating+substrate

Thermal noise from:

4

standard coating

Studies of coating loss ongoing – (see poster by G. Cagnoli)

102

103

104

10-24

10-23

10-22

Frequency [Hz]

h [H

z-1/2

]GEO-HF noise levels based on best possible coating losses

full coating, silicadoped coating, silicaaperiodic coating, silicasilica substrateaperiodic coating, sapphiresapphire substrateaperiodic coating, siliconsilicon substrate

GEO Simulated Noise – GEO Simulated Noise – high Q high Q

101

102

103

10-24

10-23

10-22

10-21

10-20

10-19

10-18

[h*H

z-1/2

]

Freq. [Hz]

Seismic

Suspension TN

Substrate TN

Coating TN

Thermorefractive

Shot

Total

Studies of silicon as a test mass Studies of silicon as a test mass substratesubstrate

Preliminary Preliminary room T measurementsroom T measurements made of mechanical dissipation of made of mechanical dissipation of bulk silicon samples suspended on bulk silicon samples suspended on silk thread or wire loopssilk thread or wire loops– Internal resonant modes of the samples Internal resonant modes of the samples

excited; decay of mode amplitude excited; decay of mode amplitude measuredmeasured

To high voltage

Excitation plate(behind mass)

Silicon samples cut along different crystal axes, [111] and [100]. The [111] sample was boron-doped.

Dissipation of two silicon samples of identical geometry, supplied by collaborators in Stanford, was measured over a range of frequencies.

Clamp

Suspension thread/wire

Schematic diagram of front view of suspended test mass.

Test mass

Shot Noise in SR IFOsShot Noise in SR IFOs

101

102

103

10-24

10-23

10-22

Freq. [Hz]

ASD

[h/

Hz]

GEO Theoretical Noise Budget

SeismicCoating TNThermorefractiveShot 1 kHzShot 200HzShot 500Hz

102

103

10-21

10-20

10-19

10-18

10-17

Frequency [Hz]

h(t

) [H

z-1/2

]

Jan 02

Aug 02 (S1)

Jan 04 (S3)

Sept 05

Feb 05 (S4)

Aug 04

GEO600 sensitivity evolutionGEO600 sensitivity evolution