| 1. |
- Schwenke, Jörg, et al.
(författare)
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Digital in-line holography on amplitude and phase objects prepared with electron beam lithography.
- 2012
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720. ; 247:2, s. 196-201
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Tidskriftsartikel (refereegranskat)abstract
- We report on the fabrication and characterization of amplitude and phase samples consisting of well defined Au or Al features formed on ultrathin silicon nitride membranes. The samples were manufactured using electron beam lithography, metallization and a lift-off technique, which allow precise lateral control and thickness of the metal features. The fabricated specimens were evaluated by conventional microscopy, atomic force microscopy and with the digital in-line holography set-up at the Lund Laser Centre. The latter uses high-order harmonic generation as a light source, and is capable of recovering both the shape and phase shifting properties of the samples. We report on the details of the sample production and on the imaging tests with the holography set-up.
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| 2. |
- Schwenke, Jörg, et al.
(författare)
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Single-shot holography using high-order harmonics
- 2008
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Ingår i: Journal of Modern Optics. - : Informa UK Limited. - 0950-0340 .- 1362-3044. ; 55:16, s. 2723-2730
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Tidskriftsartikel (refereegranskat)abstract
- This work demonstrates single-shot holography with ultrashort XUV pulses. The pulses are generated by high-harmonic generation in an Ar gas cell and focused to produce a strongly divergent reference beam suitable for in-line holography of micrometer size objects. The achieved intensity of the high-order harmonics in the XUV regime is sufficient for single-shot holography with good signal-to-noise ratio. A numerical algorithm is applied to reconstruct real images from the recorded holograms, which also includes an iterative process to reduce the twin-image blurring. Holograms and reconstructed images of microscope tips are presented and a description of the algorithm is given.
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| 3. |
- Svanberg, Sune, et al.
(författare)
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Applications of terawatt lasers
- 1994
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Ingår i: LASER SPECTROSCOPY - XITH INTERNATIONAL CONFERENCE. - : AIP. - 1551-7616 .- 0094-243X. - 1563962624 ; :290, s. 264-269
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Konferensbidrag (refereegranskat)
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| 4. |
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| 5. |
- Fordell, Thomas, et al.
(författare)
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Carrier-envelope phase stabilization of a multi-millijoule, regenerative-amplifier-based chirped-pulse amplifier system
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:23, s. 21091-21097
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Tidskriftsartikel (refereegranskat)abstract
- This article reports on the successful stabilization of the carrier-envelope phase of a 1-kHz laser system that includes a large grating stretcher, a regenerative amplifier, a multipass amplifier and a grating compressor. Phase stability for pulse energies up to 6 mJ is demonstrated using electronic feedback to the oscillator locking electronics as well as feedback via an acousto-optic programmable dispersive filter. (C) 2009 Optical Society of America
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| 6. |
- Gaarde, Mette, et al.
(författare)
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High-order tunable sum and difference frequency mixing in the xuv region
- 1996
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of tunable high-order sum and difference frequency mixing in the 7-70 eV range, in xenon, argon and neon. We mix the light from a terawatt, subpicosecond titanium-sapphire laser and that from a tunable optical parametric generator. The radiation generated through mixing processes involves absorption or emission of one or Mo photons from the weak tunable source. The relative strengths of the sum and difference frequency processes depend strongly on the wavelength range of the generated radiation. The sum frequency processes are stronger at low photon energies in xenon, whereas the difference frequency processes dominate at high photon energies, in neon, being almost comparable to harmonic generation.
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| 7. |
- He, Xinkui, et al.
(författare)
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Interference effects in two-color high-order harmonic generation
- 2010
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 82:3
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Tidskriftsartikel (refereegranskat)abstract
- We study high-order harmonic generation in argon driven by an intense 800 nm laser field and a small fraction of its second harmonic. The intensity and divergence of the emitted even and odd harmonics are strongly modulated as a function of the relative delay between the two fields. We provide a detailed analysis of the underlying interference effects. The interference changes drastically when approaching the cutoff region due to a switch of the dominant trajectory responsible for harmonic generation.
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| 8. |
- He, Xinkui, et al.
(författare)
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Spatial and spectral properties of the high-order harmonic emission in argon for seeding applications
- 2009
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 79:6
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Tidskriftsartikel (refereegranskat)abstract
- We characterize and control the harmonic emission in the spectral and spatial domains in order to define in which conditions the harmonic radiation can be a high-quality seed for soft x-ray and x-ray free-electron lasers. The length of the gas cell, where harmonics are generated, was optimized and the energy per pulse was determined in absolute value with a calibrated x-ray photodiode. The beam spatial profile was measured and, in some conditions, a very collimated beam with a half-angle divergence below 1 mrad could be obtained. We also show that increasing the intensity of the fundamental laser field leads to a considerable broadening of the bandwidth of the harmonic radiation, allowing us to cover a large spectral range. This effect is due to fundamental reshaping leading to an efficient phase matching of both short- and long-trajectory contributions.
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| 9. |
- Hunsche, S, et al.
(författare)
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Ionization and fragmentation of C-60 via multiphoton-multiplasmon excitation
- 1996
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Ingår i: Physical Review Letters. - 1079-7114. ; 77:10, s. 1966-1969
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Tidskriftsartikel (refereegranskat)abstract
- We study the intensity dependence of ionization and fragmentation of buckminsterfullerene (C-60) in strong laser fields. Our data provide strong evidence that at intensities less than or similar to 10(14) W/cm(2) these processes occur predominantly via multiphoton excitation of the 20 eV plasmon resonance of C-60 At least two plasmons have to be created to initiate fragmentation or multiple ionization.
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| 10. |
- Kovacev, M, et al.
(författare)
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Extreme ultraviolet fourier-transform spectroscopy with high order harmonics
- 2005
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Ingår i: Physical Review Letters. - 1079-7114. ; 95:22
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a new scheme for extreme ultraviolet (xuv) Fourier-transform spectroscopy based on the generation of two phase-locked high-harmonic beams. It allows us to measure for the first time interferograms at wavelengths as short as 90 nm, and open the perspective of performing high-resolution Fourier-transform absorption spectroscopy in the xuv. Our measurements also demonstrate that a precise control of the relative phase of harmonic pulses can be obtained with an accuracy on an attosecond time scale, of importance for future xuv pump-xuv probe attosecond spectroscopy.
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