The Experts below are selected from a list of 46101 Experts worldwide ranked by ideXlab platform
P B Corkum - One of the best experts on this subject based on the ideXlab platform.
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alignment dependent enhancement of the photoelectron cutoff for multiphoton ionization of molecules
Physical Review Letters, 2014Co-Authors: C. Smeenk, Ladan Arissian, Alexei V Sokolov, Michael Spanner, Kurnchul Lee, A Staudte, D M Villeneuve, P B CorkumAbstract:The multiphoton ionization rate of molecules depends on the alignment of the molecular axis with respect to the ionizing Laser Polarization. By studying molecular frame photoelectron angular distributions from ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, and benzene, we illustrate how the angle-dependent ionization rate affects the photoelectron cutoff energy. We find alignment can enhance the high energy cutoff of the photoelectron spectrum when probing along a nodal plane or when ionization is otherwise suppressed. This is supported by calculations using a tunneling model with a single ion state.
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Polarization state of high order harmonic emission from aligned molecules
Physical Review Letters, 2007Co-Authors: P B Corkum, J Levesque, Y Mairesse, Nirit Dudovich, H Pepin, Jeanclaude Kieffer, D M VilleneuveAbstract:High harmonic emission in isotropic gases is polarized in the same direction as the incident Laser Polarization. Laser-induced molecular alignment allows us to break the symmetry of the gas medium. By using aligned molecules in high harmonic generation experiments, we show that the Polarization of the extreme ultraviolet emission depends strongly on the molecular alignment and the orbital structure. Polarization measurements give insight into the molecular orbital symmetry. Furthermore, molecular alignment will allow us to produce attosecond pulses with time-dependent Polarization.
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femtosecond Laser induced long range self organized periodic planar nanocracks for applications in biophotonics
Proceedings of SPIE, 2007Co-Authors: E Simova, Cyril Hnatovsky, D M Rayner, Rod S Taylor, P B CorkumAbstract:With the proper choice of Laser parameters focused femtosecond Laser light creates long-range self-assembled planar nanocracks inside and on the surface of fused silica glass. The orientation of the crack planes is normal to the Laser Polarization direction and can be precisely controlled. The arrays of cracks when properly oriented and combined with chemical etching produce high aspect ratio micro- and nanofluidic channels. Direct femtosecond Laser writing without any chemical etching can be used to fabricate embedded nanoporous capillaries in bulk fused silica for biofiltering and electrophoresis applications. The morphology of the porous structures critically depends on the Laser Polarization and pulse energy and can be used to control the transmission rates of fluids through the capillaries. Finally high aspect ratio, Polarization-dependent, self-ordered periodic nanoslots can be fabricated from nanocracks produced on the surface of fused silica wafers. Control of the surface slot width from 10 to 60 nm is achieved through selective chemical etching. This technique, which may be useful for Surface Enhanced Raman Scattering (SERS) applications, has sub-diffraction limited resolution and features high throughput writing over centimeters.
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optically produced arrays of planar nanostructures inside fused silica
Physical Review Letters, 2006Co-Authors: V R Bhardwaj, Cyril Hnatovsky, R S Taylor, E Simova, D M Rayner, P P Rajeev, P B CorkumAbstract:Linearly polarized femtosecond light pulses, focused inside fused silica to an intensity that leads to multiphoton ionization, produce arrayed planes of modified material having their normal parallel to the Laser Polarization. The planes are $\ensuremath{\le}10\text{ }\text{ }\mathrm{nm}$ thick and are spaced at $\ensuremath{\sim}\ensuremath{\lambda}/2$ in the medium for free space wavelengths of both 800 and 400 nm. By slowly scanning the sample under a fixed Laser focus, order is maintained over macroscopic distances for all angles between the Polarization and scan direction. With the Laser Polarization parallel to the scan direction we produce long-range Bragg-like gratings. We discuss how local field enhancement influences dielectric ionization, describe how this leads to nanoplane growth, why the planes are arrayed, and how long-range order is maintained.
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Polarization selective etching in femtosecond Laser assisted microfluidic channel fabrication in fused silica
Optics Letters, 2005Co-Authors: Cyril Hnatovsky, R S Taylor, E Simova, V R Bhardwaj, D M Rayner, P B CorkumAbstract:We fabricate microchannels in fused silica by femtosecond Laser irradiation followed by etching in diluted hydrofluoric acid. We show a dramatic dependence of the etch rate on the Laser Polarization, spanning 2 orders of magnitude. We establish the existence of an energy-per-pulse threshold at which etching of the Laser-modified zones becomes highly Polarization selective. The enhanced selective etching is due to long-range, periodic, Polarization-dependent nanostructures formed in the Laser-modified material.
Angel Rubio - One of the best experts on this subject based on the ideXlab platform.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing the microscopic mechanism of high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals; (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential; the yield is increased for heavier atoms; and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
M A Camacholopez - One of the best experts on this subject based on the ideXlab platform.
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Laser induced periodic surface structures on bismuth thin films with ns Laser pulses below ablation threshold
Optical Materials Express, 2017Co-Authors: A Reyescontreras, M A Camacholopez, Santiago Camacholopez, Oscar Oleamejia, A Esparzagarcia, J G BanuelosmunetonAbstract:We demonstrate the formation of Laser-induced periodic surface structures (LIPSS) in bismuth (Bi) thin films by irradiation with nanosecond Laser pulses. We report on the formation and the destruction of the LIPSS as a result of the delivered number of pulses; both the formation and destruction threshold were very well determined. Results show that the obtained LIPSS are perpendicular to the Laser Polarization, and their ripple periodicity is on the order of the irradiation wavelength. Although all the irradiation experiments were done in ambient air, Raman micro-spectroscopy indicates that the LIPSS are constituted by metallic bismuth, i. e. the LIPSS formation is oxidation free.
B M Hegelich - One of the best experts on this subject based on the ideXlab platform.
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three dimensional dynamics of breakout afterburner ion acceleration using high contrast short pulse Laser and nanoscale targets
Physical Review Letters, 2011Co-Authors: Lin Yin, B J Albright, K J Bowers, D Jung, J C Fernandez, B M HegelichAbstract:Breakout afterburner (BOA) Laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to Laser Polarization and propagation. Analytic theory presented for the electron dynamics in the Laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric Laser intensity profile; these results are consistent with recent experiments at the Trident Laser facility.
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radiation pressure acceleration of ion beams driven by circularly polarized Laser pulses
Physical Review Letters, 2009Co-Authors: A Henig, D Jung, B M Hegelich, S Steinke, M Schnurer, T Sokollik, Rainer Horlein, Daniel Kiefer, Jorg Schreiber, J MeyertervehnAbstract:We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast Laser pulses of energy 0.7 J focused to peak intensities of 5x10{sup 19} W/cm{sup 2}. A reduction in electron heating is observed when the Laser Polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those C{sup 6+} ions are for the first time dominantly accelerated in a phase-stable way by the Laser radiation pressure.
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radiation pressure acceleration of ion beams driven by circularly polarized Laser pulses
Physical Review Letters, 2009Co-Authors: A Henig, D Jung, B M Hegelich, S Steinke, M Schnurer, T Sokollik, Rainer Horlein, Daniel Kiefer, Jorg Schreiber, X Q YanAbstract:We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast Laser pulses of energy 0.7 J focused to peak intensities of $5\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$. A reduction in electron heating is observed when the Laser Polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those ${\mathrm{C}}^{6+}$ ions are for the first time dominantly accelerated in a phase-stable way by the Laser radiation pressure.
Nicolas Tancognedejean - One of the best experts on this subject based on the ideXlab platform.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
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impact of the electronic band structure in high harmonic generation spectra of solids
Physical Review Letters, 2017Co-Authors: Nicolas Tancognedejean, Oliver D. Mücke, Franz X. Kärtner, Angel RubioAbstract:An accurate analytic model describing the microscopic mechanism of high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that (i) the emitted HHG spectra are highly anisotropic and Laser-Polarization dependent even for cubic crystals; (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential; the yield is increased for heavier atoms; and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the Laser Polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.
