Molecular variation of capillary-produced soft x-ray high harmonics

Stebbings, Sarah L.; Rogers, Edward T. F.; Paula, Ana; Praeger, Matthew; Froud, C.A.; Mills, B.; Hanna, D.C.; Baumberg, Jeremy J.; Brocklesby, W.S.; Frey, Jeremy G.

doi:10.1088/0953-4075/41/14/145602

Cited by 5 publications

(18 citation statements)

References 29 publications

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“…This process occurs every half cycle of the laser pulse -multi cycle driving laser pulses will result in a series of SXR photon bursts which will coherently interfere. Fourier transforming this interference yields the characteristic high harmonic spectrum (Stebbings et al, 2008). The spectrum is a comb of frequencies up to a maximum energy known as the cut-off, E max , is given by equation (1).…”

Section: Semi-classical and Quantum Mechanical Approaches To High Harmentioning

confidence: 99%

“…A pair of two 300 μm diameter holes were drilled 2 cm from either end of the waveguide that allow gas, typically argon, to be fed into the capillary and defining a central region of constant pressure. (Stebbings et al, 2008).…”

Section: Capillary High Harmonic Generationmentioning

confidence: 99%

“…This is then used to calculate the phase mismatch, Δk, according to equation 7. (Stebbings et al, 2008) …”

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

“…The phase mismatch is then substituted into equation 8 in order to determine the intensity as a function of position, r, time, t, and harmonic order, q. (Stebbings et al, 2008) The maximum intensity has also been normalised to 1. Reproduced with permission from Institute of Physics Publishing Ltd (Stebbings et al, 2008).…”

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

“…(Stebbings et al, 2008) The maximum intensity has also been normalised to 1. Reproduced with permission from Institute of Physics Publishing Ltd (Stebbings et al, 2008).…”

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

See 4 more Smart Citations

An Attosecond Soft x-ray Nanoprobe: New Technology for Molecular Imaging

Stebbings¹,

Frey²,

Brocklesby³

2010

Advances in Solid State Lasers Development and Applications

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Section: Semi-classical and Quantum Mechanical Approaches To High Harmentioning

confidence: 99%

Section: Capillary High Harmonic Generationmentioning

confidence: 99%

“…This is then used to calculate the phase mismatch, Δk, according to equation 7. (Stebbings et al, 2008) …”

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

“…(Stebbings et al, 2008) The maximum intensity has also been normalised to 1. Reproduced with permission from Institute of Physics Publishing Ltd (Stebbings et al, 2008).…”

Section: Molecular Variation Of Capillary-produced Sxrsmentioning

confidence: 99%

See 3 more Smart Citations

An Attosecond Soft x-ray Nanoprobe: New Technology for Molecular Imaging

Stebbings¹,

Frey²,

Brocklesby³

2010

Advances in Solid State Lasers Development and Applications

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Geometry- and diffraction-independent ionization probabilities in intense laser fields: Probing atomic ionization mechanisms with effective intensity matching

et al. 2006

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We report a novel experimental technique for the comparison of ionization processes in ultrafast laser pulses irrespective of pulse ellipticity. Multiple ionization of xenon by 50 fs 790 nm, linearly and circularly polarized laser pulses is observed over the intensity range 10 TW/cm 2 to 10 PW/cm 2 using Effective Intensity Matching (EIM), which is coupled with Intensity Selective Scanning (ISS) to recover the geometry-independent probability of ionization. Such measurements, made possible by quantifying diffraction effects in the laser focus, are compared directly to theoretical predictions of multiphoton, tunnel and field ionization, and a remarkable agreement demonstrated. EIM-ISS allows the straightforward quantification of the probability of recollision ionization in a linearly polarized laser pulse. Furthermore, probability of ionization is discussed in terms of the Keldysh adiabaticity parameter γ, and the influence of the precursor ionic states present in recollision ionization is observed for the first time.

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Bright extreme-ultraviolet high-order-harmonic radiation from optimized pulse compression in short hollow waveguides

et al. 2013

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Multimodal nonlinear propagation dominates the evolution of intense laser pulses propagating in high pressure gas-filled capillaries used for high harmonic generation. A fully multimodal nonlinear propagation model is used to predict pulse evolution along such a capillary, and the length and pressure distribution optimised to produce the shortest pulses at the capillary output. This optimisation is shown theoretically to result in self compression of the pulse from ∼53 fs to ∼7 fs, and shown experimentally to increase the flux of high harmonic radiation from the capillary by an order of magnitude over comparable capillary and gas jet designs.PACS numbers: 42.65. Ky, 42.65.Re At optical intensities above > 10 13 W cm −2 the onset of tunnel ionisation allows for the observation of intense high-order harmonic generation (HHG) within atomic [1] and molecular gases [2]. Thanks to their small experimental footprint, high achievable photon energies and high coherence, lab-scale HHG-based sources have an array of potential applications if high photon flux in the extreme ultraviolet (XUV) and soft x-ray wavelength ranges can be generated.High photon flux HHG requires many different criteria to be fulfilled. At relatively low intensities and gas densities, the fraction of the target gas which is ionised is low, and the plasma generated as a result of ionisation has a low density. Thus, propagation of the pump pulse is close to linear, and any effect of depletion of the ground state of the gas atoms can be neglected. Under these conditions, elegant solutions have been proposed for phase matching in gas jets using the Gouy shift[3] and in gas-filled capillaries using modal dispersion [4]. In capillaries, quasi-phasematching via linear propagation based techniques such as variation in capillary geometry [5] and mode-beating [6] have been demonstrated.As laser intensities and gas pressures are increased, both the ionisation fraction and the plasma density can become large. In this case, ground state depletion and nonlinear propagation both act to make efficient generation harder to achieve. Generation in gas jets using very short (<10 fs) pulses has been shown to improve harmonic yield at high intensities [7], by reducing ground state depletion at the peak of the pulse. The effect of nonlinear propagation on phase matching is also reduced, because the leading edge of the pulse sees much lower plasma density. Within a capillary waveguide, the generation of large densities of plasma causes significant nonlinear coupling between capillary modes, which redistributes energy between modes as a function of propagation distance. Thus phase matching based on the excitation of a single mode or combination of modes along the entire capillary will be severely degraded.Nonlinear propagation effects can, however, be useful within the capillary waveguide. At low gas pressures (<10 mbar) within the capillary, self compression of propagating pulses by a factor of ∼2.3 has previously been observed [8] under conditions of high ionisation fra...

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Molecular variation of capillary-produced soft x-ray high harmonics

Cited by 5 publications

References 29 publications

An Attosecond Soft x-ray Nanoprobe: New Technology for Molecular Imaging

An Attosecond Soft x-ray Nanoprobe: New Technology for Molecular Imaging

Geometry- and diffraction-independent ionization probabilities in intense laser fields: Probing atomic ionization mechanisms with effective intensity matching

Bright extreme-ultraviolet high-order-harmonic radiation from optimized pulse compression in short hollow waveguides

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