Jeremy Allington-Smith AstroPhotonica Europa coordinator Centre for Advanced Instrumentation Durham...

Jeremy Allington-Smith

Jeremy Allington-SmithAstroPhotonica Europa coordinator

Centre for Advanced InstrumentationDurham University

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Astrophotonics promiseAstrophotonics promiseOpticon Board Meeting 10-11 Nov 2008, Porto

This talk focusses on PROMISEnot PROGRAMMATICS


AcknowledgementsAcknowledgements

Pierre Kern* (LAOGrenoble)

Joss Bland-Hawthorn* (U. Sydney; AAO)

Martin Roth* (AIP)

Robert Thomson (Heriot Watt U)

Tim Birks (U. Bath)

Jason Corbett (CfAI, Durham U+)

... and their associates

... and all our partners in AstroPhotonica Europa (includes Porto, ESO, MPIA…..)

* Opticon-FP7 co-investigators, + now at Malvern Instruments


What is it?What is it?

AstrophotonicsAstrophotonics = = AstronomyAstronomy + + PhotonicsPhotonics

The application of photonic principles and devices to astronomyThe application of photonic principles and devices to astronomy

Astrophotonica EuropaAstrophotonica Europa == a European partnership to achieve this goala European partnership to achieve this goal


Why we need itWhy we need it

• Main themes for astronomy– Equation of state of the universe– Galactic archaelogy – Extrasolar planets; AGN studies

→ large aperture and high spatial resolution → ELTs → very high spatial resolution → LBOIRI

AstroPhotonics AstroPhotonics can bring major benefits to:can bring major benefits to:

– Highly-multiplexed spectroscopy – a critical technique -

– Specific technical problems for ELTs to be solved– Improved utility of long-baseline opt/IR interferometry– Pre-dispersion removal of telluric background


What actually is photonics?What actually is photonics?

Examples:• Photonic crystal fibres (1-D)• Slab waveguides (2-D; VPHg

a very simple example)• Waveguide arrays (3-D)

The behaviour of a medium The behaviour of a medium depends not only on the depends not only on the type of its constituent type of its constituent atoms but also on the atoms but also on the geometrical layout of the geometrical layout of the atomic oscillatorsatomic oscillators


Index guidanceIndex guidance

β=kn

n=β/k

1.45 1.40

Core

Cladding (eff)

Reflection of light from medium of index higher than that of cladding

β=kn

n=β/k

1.40

1.00

Cladding (eff)

Air

Reflection of light from medium of index lower than that of the cladding

Photonic band-gapPhotonic band-gap

c =2π f

k2 fv π

β=

n

core> β

k> ncladding

Photonics in 1D: PCFsPhotonics in 1D: PCFs


ApplicationsApplications

• PCF capabilities• Long-baseline interferometry• OH suppression• Highly-multiplexed spectroscopy • Miniaturisation for ELTs


New fibre technologyNew fibre technology

• Extended wavelength range for PCFs:– Endlessly single mode (interferometry)

– New materials and construction for e.g. infrared

• Fibres designed for multiplexing– Multicore + “nano-lens” arrays = micro IFUs

• Telluric background rejection– Suppression of airglow forest

• Etendue conservation via single modes ?– No Focal ratio degradation

– Large coupling interface (mode area; LMA)

~10 recent papers by AAO & Durham


Interferometry Interferometry (long-baseline (long-baseline opt/IR)opt/IR)

• Long heritage in interferometry: FLUOR, OHANA, IONIC

• Specific photonic solutions for critical functions:

– beam combination

– light transport (PCF junctions/switches)

• Integrated Optics to simplify complexity of multilayer systems via e.g….

• On-chip integration - e.g. novel fringe tracker via Lipmann interfometry Single photon detectors

(Grenoble Quantum Dots (St Andrews, ATC)

Brief summary - interface with interferometry and fast detectors activities in OPTICON


OH suppressionOH suppression

NIR airglow emission artefacts & reduced SNR

Extended wings due to disperser Remove before dispersion

Currently limited by number of modes coupled from telescope

* OpEx, 12, 5902 ** Opt. Lett. 30 2545

Bland-Hawthorn et al. (2004)*; Leon-Saval et al, (2005)**

2

2

dM

πλΞ⎛ ⎞=⎜ ⎟

⎝ ⎠

ΞΞ = Numerical aperture= Numerical aperture

d = fibre core diameter d = fibre core diameter

(40-100(40-100µm)µm)

10 < M <10010 < M <100

Multimodefibre

Multimodefibre

Bragg gratingson singlemodeMM PCFs


x

y

λ

Datacube

Multiplexed spectroscopyMultiplexed spectroscopy

MOS• Must dilutely sample field

due to detector cost• Need arbitrary choice of

spaxels contiguous or not• MOS+IFS = Diverse Diverse Field Field SpectroscopySpectroscopy

Celestial SelectorFor DFS

Primary feed

Switcher

Spectrograph feed

Telescope focus

Selected regions

Spectrograph slit

Observationcontrol

Spectrographs

Recorded spectra

•Integrated optics•Tiny replicated spectrometers•Novel fibres (PCFs)

Murray & Allington-Smith (in prep)Allington-Smith, Murray & Padgett (in prep)


R. Content et al. (Durham)

Miniaturising instruments?Miniaturising instruments?

• Gigantic integral field unit for ELT (GSMT)

• 3'x3' @0.1" IFU• Beam size ~250mm• R = 2000

Fore-optics & pickoff mirrors

Dimensions:6 x 7 x 8m

Reduce volume by factor 50?Reduce volume by factor 50?

Thomson, Kar & Allington-Smith (2008)


Telescopefocus

Massively multiplexedSliced/IFU

Photonic spectrographPhotonic spectrograph

Multimodefibres

DataMulti-mono

mode transition

ArrayedWaveguide

Grating

LinearDetector

array

Integrated Photonic spectrograph Multi-mono

mode transition

ArrayedWaveguide

Grating

LinearDetector

array


mode transition

ArrayedWaveguide

Grating

LinearDetector

array


mode transition

ArrayedWaveguide

Grating

LinearDetector

array


mode transition

PhotonicDisperser

(AWG,Lipmann)

LinearDetector

array

Integrated Photonic spectrograph

One miniature integrated One miniature integrated photonic spectrograph per fibrephotonic spectrograph per fibre

One miniature integrated One miniature integrated photonic spectrograph per fibrephotonic spectrograph per fibre

Demonstrated Demonstrated but not in but not in

integrated deviceintegrated device

Demonstrated Demonstrated but not in but not in

integrated deviceintegrated device

Devices exist but Devices exist but not integrated to not integrated to

detectordetector

Devices exist but Devices exist but not integrated to not integrated to

detectordetector

Exists but notExists but notintegrated inintegrated inspectrographspectrograph

Exists but notExists but notintegrated inintegrated inspectrographspectrograph


Photonic disperser: Photonic disperser: AWGAWG

Arrayed Waveguide Gratings avoid geometrical limits of SL gratings using phased fibre arrays

• Potential size advantage of 5-10 in linear size; cost factor 30-1000! (Bland-Hawthorn et al., AAO)


Photonic disperser: Photonic disperser: “SWIFTS”“SWIFTS”

• Detect evanescent field in waveguide

• Detectors?– SSPD – Quantum dots

LeCoarer et al. Nature Photonics 1, 473 (2007)


Enabling tchnology: ULIEnabling tchnology: ULI

• OHS by multi-singlemode transitions and photonic phased array dispersers need 3D waveguide networks

• Thomson, Kar & Allington-Smith (OpEx submitted) propose

Ultrafast laser inscription (Thomson et al. OpEx 15, 11691 (2007).

• Highly focussed, steerable laser changes refractive index in suitable materials when power density exceeds a threshold near focus


ULI 3D waveguidesULI 3D waveguides

• OHS: Replace complicated PCF transition with mass-producible units

• Photonic disperser: maximise phase shift via spiral geometry


OrganisationOrganisation

• Exploit recent advances in Photonics by telecommunications industry

• Build on Europe’s innovation heritage (e.g IFS)• Get together with your friends

→ AstroPhotonica Europa partnership


AAstrostroPPhotonica hotonica EEuropauropaPartnership Partnership

UK/France/Germany/Netherlands/Spain/PortugalUK/France/Germany/Netherlands/Spain/Portugal

• Astronomy InstitutesAstronomy Institutes• Photonics institutesPhotonics institutes• Foundries (detailed design and prototyping)Foundries (detailed design and prototyping)

FundingFunding• EU via OPTICON (FP7 support)EU via OPTICON (FP7 support)• National and regional funding (e.g. InnoFspec, Potsdam)National and regional funding (e.g. InnoFspec, Potsdam)• In-kind contributions of effort and facilitiesIn-kind contributions of effort and facilities

ActivitiesActivities• Workshops & NetworkingWorkshops & Networking• Research & assessmentResearch & assessment

SynergiesSynergies• Regional optics technology networks & IndustryRegional optics technology networks & Industry

A European research partnership


AAstrostroPPhotonica hotonica EEuropauropaA European research partnership


AAstrostroPPhotonica hotonica EEuropauropaA European research partnership

Further informationFurther information Contact co-ordinatorContact co-ordinator

[email protected]@durham.ac.uk

http://star-www.dur.ac.uk/~jra/astrophotonica.htmlhttp://star-www.dur.ac.uk/~jra/astrophotonica.html


ConclusionsConclusions

• To understand the origins of the cosmos and of To understand the origins of the cosmos and of ourselves astronomers needs new technologyourselves astronomers needs new technology

• Exploitation of photonic principles and devices Exploitation of photonic principles and devices already developedalready developed will help us do this will help us do this

• Without it, instrumentation for the next Without it, instrumentation for the next generation of telescopes may run into major generation of telescopes may run into major problemsproblems

• Find out more!Find out more!


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