The Application of High-Order Harmonics to Extreme Ultraviolet Polarimetry

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The Application of The Application of High-Order Harmonics High-Order Harmonics to Extreme Ultraviolet to Extreme Ultraviolet PolarimetryPolarimetry

N. Brimhall, J. C. Painter, M. Turner, R. S. N. Brimhall, J. C. Painter, M. Turner, R. S. Turley, M. Ware, J. Peatross Turley, M. Ware, J. Peatross

Brigham Young University, Provo, UT 84602.Brigham Young University, Provo, UT 84602.

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Motivation/ApplicationsMotivation/Applications High Harmonics as an EUV sourceHigh Harmonics as an EUV source Prototype ExperimentPrototype Experiment Full-scale instrument in progressFull-scale instrument in progress

Development of an instrument that utilizes laser Development of an instrument that utilizes laser generated high order harmonics as a source generated high order harmonics as a source of extreme ultraviolet light for polarimetry. of extreme ultraviolet light for polarimetry.

OverviewOverview

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Motivation/Motivation/ApplicationsApplications

http://www.esa.int/esaCP/index.htmlhttp://www.esa.int/esaCP/index.html

IMAGE satelliteIMAGE satellite

Mars ExpressMars Express

Venus ExpressVenus Express

http://euv.lpl.arizona.edu/euv/http://euv.lpl.arizona.edu/euv/

Astronomy, Lithography, Microscopy, Astronomy, Lithography, Microscopy, Plasma DiagnosticsPlasma Diagnostics

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The complex index The complex index of refraction of refraction ((NN = 1- = 1-δδ+i+iββ)) for one or more for one or more materials differed materials differed significantly from significantly from published values.published values.

These values had to These values had to be re-measured to be re-measured to achieve the desired achieve the desired specifications.specifications.

A Problem is A Problem is DiscoveredDiscovered

http://euv.lpl.arizona.edu/euv/http://euv.lpl.arizona.edu/euv/

55

Edges in published constants are different by as much Edges in published constants are different by as much as 3 eV from measured values.as 3 eV from measured values.

Graph of published Graph of published

optical constants of optical constants of

ThO2 versus ThO2 versus

measured values.measured values.

Inaccuracies in Inaccuracies in published optical published optical constantsconstants

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800 nm, 35 fs, 10 mJ Ti:sapphire laser focused in He, Ne, 800 nm, 35 fs, 10 mJ Ti:sapphire laser focused in He, Ne, Ar, or Xe gas produces EUV lightAr, or Xe gas produces EUV light

An EUV Polarimeter An EUV Polarimeter Based on High-Order Based on High-Order HarmonicsHarmonics

Used in a Used in a polarimeter, polarimeter, this source is this source is CheapCheap TabletopTabletop LocalLocal

J. R. Sutherland et al, Optics J. R. Sutherland et al, Optics Express 12, 4430-4436 (2004).Express 12, 4430-4436 (2004).

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hellohello

SpecificationsSpecificationsHigh Harmonic Generation High Harmonic Generation at BYUat BYU

Beamline 6.3.2 at the Beamline 6.3.2 at the Advanced Light SourceAdvanced Light Source

Hollow Cathode Hollow Cathode Plasma Source at BYUPlasma Source at BYU

EnergyEnergy 20-155 eV (8-62 nm), quantized as 1.55q where q is a positive odd integer (roughly every 3 eV)

50-1300 eV (1-25 nm) continuous.

Various atomic and ionic emission lines from 10-177 eV (7-121.6 nm). Comprises approximately 150 lines.

FluxFlux 6x108 photons/sec @100 eV (measured)

1011 photons/sec @100 eV (calculated)

2x103 photons/sec @41 eV (measured)

Spectral Resolution Spectral Resolution (E/ΔE)(E/ΔE)

>50 7000 >500

PolarizationPolarization Rotatable linear polarization, same as laser.

90% s-polarized, 10% p-polarized

Unpolarized

Angular ResolutionAngular Resolution 0.06º ~0.02º 0.08º

DetectorsDetectors Microchannel plate (MCP) Photodiode, channeltron, CCD

Channeltron

Spot Size at SampleSpot Size at Sample 1000 x 1000 μm 10 x 300 μm 5000 x 5000 μm

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hellohello

SpecificationsSpecificationsHigh Harmonic High Harmonic Generation at BYUGeneration at BYU

Beamline 6.3.2 at the Beamline 6.3.2 at the Advanced Light Advanced Light SourceSource

Hollow Cathode Hollow Cathode Plasma Source at Plasma Source at BYUBYU

EnergyEnergy 20-155 eV (8-62 nm), 20-155 eV (8-62 nm), quantized as 1.55q where quantized as 1.55q where q is a positive odd integer q is a positive odd integer (roughly every 3 eV)(roughly every 3 eV)

50-1300 eV (1-25 nm) 50-1300 eV (1-25 nm) continuous.continuous.

Various atomic and Various atomic and ionic emission lines ionic emission lines from 10-from 10-177 eV (7-121.6 nm). 177 eV (7-121.6 nm). Comprises Comprises approximately 150 approximately 150 lines.lines.





>50 7000 >500



Unpolarized


DetectorsDetectors Microchannel plate (MCP) Photodiode, channeltron, CCD Channeltron


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hellohello







FluxFlux 6x106x1088 photons/sec @100 photons/sec @100 eV (measured)eV (measured)

10101111 photons/sec @100 photons/sec @100 eV (calculated)eV (calculated)

2x102x1033 photons/sec photons/sec @41 eV (measured)@41 eV (measured)


>50 7000 >500



Unpolarized




1010

hellohello


Beamline 6.3.2 at Beamline 6.3.2 at the Advanced Light the Advanced Light SourceSource








Spectral Spectral Resolution Resolution (E/ΔE)(E/ΔE)

>50>50 70007000 >500>500



Unpolarized




1111

hellohello











>50 7000 >500

PolarizationPolarization Rotatable linear Rotatable linear polarization, same as polarization, same as laser.laser.

90% s-polarized, 10% 90% s-polarized, 10% p-polarizedp-polarized

UnpolarizedUnpolarized




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Demonstrated feasibilityDemonstrated feasibility Show that the source will have sufficient brightness to Show that the source will have sufficient brightness to

measure reflectances as low as 0.5%.measure reflectances as low as 0.5%.

Prototype Prototype ExperimentExperiment

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Rotatable linear polarizationRotatable linear polarization Increased scanning abilityIncreased scanning ability Ability to measure reflectance of multiple wavelengths Ability to measure reflectance of multiple wavelengths

simultaneouslysimultaneously

Full-scale instrumentFull-scale instrument

1414

hellohello

Scanning abilityScanning ability

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Normalization of reflectances with a highly Normalization of reflectances with a highly variable source.variable source.

Sample alignmentSample alignment Determination of sample and detector Determination of sample and detector

angles and detected wavelengthsangles and detected wavelengths LabView programming for automated LabView programming for automated

positioningpositioning Comparison with other EUV reflectometers Comparison with other EUV reflectometers

and polarimeters (plasma sources, and polarimeters (plasma sources,

synchrotron sources)synchrotron sources)

Questions we are Questions we are addressingaddressing

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This project promises a useful research tool to This project promises a useful research tool to the EUV thin-film researchers at BYU .the EUV thin-film researchers at BYU .

High harmonics as a source of EUV light High harmonics as a source of EUV light constitute a broad range of wavelengths from 8 constitute a broad range of wavelengths from 8 nm to 62 nm with a flux a factor of 200 times nm to 62 nm with a flux a factor of 200 times below that available at Beamline 6.3.2 at the below that available at Beamline 6.3.2 at the Advanced Light Source, but a factor of 30,000 Advanced Light Source, but a factor of 30,000 times brighter than a plasma source currently times brighter than a plasma source currently used at BYU. used at BYU.

The well-controlled polarization and the ability to The well-controlled polarization and the ability to measure reflectances simultaneously over a measure reflectances simultaneously over a wide comb of wavelengths are clear advantages.wide comb of wavelengths are clear advantages.

Our prototype instrument demonstrated the Our prototype instrument demonstrated the feasibility of this instrument and showed that we feasibility of this instrument and showed that we can measure reflectances as low as 0.5%. can measure reflectances as low as 0.5%.

Conclusions/Conclusions/SummarySummary

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Thanks to the high harmonics research Thanks to the high harmonics research group at Brigham Young University…group at Brigham Young University…

……including Sergei Voronov and Greg including Sergei Voronov and Greg Harris for their work on the prototype Harris for their work on the prototype instrument.instrument.

This project was supported by the This project was supported by the National Science Foundation Grant #PHY-National Science Foundation Grant #PHY-0457316 and by Brigham Young 0457316 and by Brigham Young University. University.

AcknowledgementsAcknowledgements

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The Application of High-Order Harmonics to Extreme Ultraviolet Polarimetry

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