Attosecond technology meeting RAL: 7/12/2005

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Attosecond technology meeting RAL 7/12/2005

• Imperial College XUV Attosecond Beamline
• progress and results to date
• Charles Haworth
• Laser Consortium
• Imperial College London
• Supervisor Dr. John Tisch

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Creation of isolated attosecond pulses


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The few-cycle driving laser
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IR Pulse measurement with FROG
Experimental trace
Retrieved trace
Wavelength (nm)
Wavelength (nm)
Time (fs)
Time (fs)
Retrieved temporal amplitude phase
Retrieved spectral amplitude phase
Wavelength (nm)
Time (fs)
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The few-cycle driving laser
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Fast phase stabilisation
A. Baltuska, et al., Nature 421, 611 (2003)
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Tunable pulse duration
0 bar
2.5 bar neon - chirped
2.5 bar neon
1.5 bar neon
Pressure tuning of pulse duration Adjustment of
gas pressure in differentially pumped fibre
permits the generation of near-transform-limited
pulses in the range 7-30fs, with constant energy
and alignment. This provides clean pulses without
significant satellites c.f. chirping maximum
bandwidth, which introduces significant pulse
distortion due to the modulated nature of the
self-phase modulated spectrum.
FWHM 28fs
FWHM 7fs
FWHM 18.5fs
FWHM 18.5fs
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High harmonic generation
f40cm mirror
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Harmonic spectrum
Measured harmonic spectra
Calculated harmonic spectra
Divergence
46nm
Wavelength
12nm
Divergence
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XUV SPIDER
Spatially Resolved HHG Spectra (initial data!)
Spatially encoded XUV SPIDER Preliminary
tests Fringing observed in the harmonic signal
from two spatially separated foci We have
observed very clear spatial and spectral fringes
in the harmonic spectra
nozzle
100µm
plasma
plasma
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Fringes in harmonic spectra
Latest fringe data (much cleaner and controllable)
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Atomic streak camera
Drescher, Science,291 pg1923,2001
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MoSi Mirror
X-ray UHV mirror mount for atomic streak camera
Engineering the atomic streak camera for
metrology of attosecond pulses Developing methods
of coring and mounting the MoSi multilayer mirror
used as the XUV/IR delay stage. Testing needle
gas targets
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Coring process
Cored two-part mirror Have MoSi mirror from NTT
Japan (13nm centre wavelength, 10 bilayers) Tests
indicate that core can be cut in-house with
minimal damage to the substrate and
coating Damage occurs close to the cut and should
not adversely affect focusing of either the XUV
or infrared pulses.
core
cutting gap (kerf)
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Atto management meeting 09/05
MoSi multilayer 2-part mirror for Atomic Streak
Camera
Centre part mounted on stalk ready for attachment
to piezo stage
Annular part mounted in UHV motorised mount
4mm
5mm
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MoSi mirror profile
Mirror reflectivity
Mirror phase
CXRO website http//www.cxro.lbl.gov/
Wavelength (nm)
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Neon HHG spectrum
Lineout of harmonic spectrum
Reflected XUV spectrum
Intensity (arb. units)
Wavelength (nm)
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Neon harmonics - Continuum
300as pulse duration
Intensity
Limited by MoSi mirror bandwidth!
Time
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New beamline!!!!!
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Acknowledgements

• Thanks to.
• John,Jon and Roland
• Joe Robinson
• Andy Gregory and Peter Ruthven
• All the other atto people!