The generation and utilisation of half‐cycle cut‐offs in high harmonic spectra

Chipperfield, L. E.; Robinson, Joseph S.; Knight, Peter; Marangos, Jonathan P.; Tisch, J. W. G.

doi:10.1002/lpor.200900028

Cited by 12 publications

(13 citation statements)

References 74 publications

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“…(1) and (4) are solved by using the Crank-Nicholson routine in the frequency domain. Once the harmonic field at the exit face (near field) of the medium is computed, the harmonics propagating in free space in the far field can be obtained from near-field harmonics through a Hankel transformation [47][48][49].…”

Section: A Propagation Equations Of Fundamental and Harmonic Fieldsmentioning

confidence: 99%

Generation of isolated attosecond pulses in the far field by spatial filtering with an intense few-cycle mid-infrared laser

Jin

Trallero–Herrero

et al. 2011

Phys. Rev. A

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We report theoretical calculations of high-order harmonic generation (HHG) of Xe with the inclusion of multielectron effects and macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. By using the time-frequency analysis we show that the reshaping of the fundamental laser field is responsible for the continuum structure in the HHG spectra. We further suggest a method for obtaining an isolated attosecond pulse (IAP) by using a filter centered on axis to select the harmonics in the far field with different divergence. We also discuss the carrier-envelope-phase dependence of an IAP and the possibility to optimize the yield of the IAP. With intense few-cycle mid-infrared lasers, this offers a possible method for generating isolated attosecond pulses.

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Section: A Propagation Equations Of Fundamental and Harmonic Fieldsmentioning

confidence: 99%

Generation of isolated attosecond pulses in the far field by spatial filtering with an intense few-cycle mid-infrared laser

Jin

Trallero–Herrero

et al. 2011

Phys. Rev. A

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“…π ω of the waveform, CE ϕ affects the evolution of nonlinear electron phenomena driven by ( ) F t , including high-order harmonic generation [5,6], ionization of atoms and molecules [7][8][9], interaction with plasmas [10], as well as photoemission from metals [11,12] and nanoparticles [13]. Attosecond control over these processes calls for control and full characterization of the applied electric field ( ) F t .…”

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confidence: 99%

Solid-state light-phase detector

et al. 2014

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The electric field of a laser pulse can be described as Here we report the first method permitting absolute CEP detection with a solid-state detector applicable in ambient conditions. Recently, we have shown that the strong electric field of an intense, linearly-polarized, visible/near-infrared (VIS/NIR), few-cycle laser pulse can rapidly increase the (ac) conductivity of a solid insulator, allowing electric currents to be induced and switched with the field of visible light [22]. In these experiments, we exposed amorphous silicon dioxide (bandgap g 9 eV E ≈ ) to a strong, controlled electric field ( ) F t of a few-cycle pulse with a carrier photon energy of ∆ is a consequence of dispersive pulse broadening inside the glass wedges. However, in our experiments P ( ) Q l ∆ was still detectable above the noise level for values of 400 µm l ∆ > , corresponding to a pulse duration of more than 9 fs (FWHM of the time-dependent cycle-averaged intensity). Subsequently, PQ was calibrated with respect to the absolute CEP of the laser pulse via stereo-ATI measurements performed with identical pulses [4]. After the measurement of P ( ) Q l ∆ with the solid-state device, a mirror was inserted into the beam path, deflecting the 5 pulses into a stereo-ATI apparatus located -together with the solid-state detector -in the same vacuum chamber (Fig. 1). Here, the CEP of the incident laser pulse was detected by analyzing the kinetic energy distribution of electrons that are photoemitted from Xe atoms, see Methods Summary. An uncertainty due to a Gouy phase shift in both foci can be neglected since in both experiments, the sample was placed exactly in the region of the highest laser intensity.We set 17 different propagation lengths l ∆ , ranging from 21.5 µm − to 27.5 µm +. For each of them, 500 single-shot stereo-ATI measurements were performed. Because consecutive laser pulses had a CEP-shift of π , which is only required for the accurate detection of P ( ) Q l ∆ , only spectra from odd-numbered pulses were considered for the stereo-ATI measurements. As shown in [4], CEϕ can then be reconstructed by calculating two asymmetry parameters ( , ) X Y by integrating the averaged time-of-flight spectra L,R TOF ( ) n t of the electrons photoemitted from Xe atoms by the intense few-cycle VIS/NIR pulses in two different regions. The parametric plot of ( , ) X Y in Fig. 2(a) was obtained by calculating, for each. The photoelectron spectra L,R TOF ( ) n twere measured with the left (L) and right (R) micro-channel plates (MCPs) of the set-up in Fig. 1 We have compared the results of the solid-state-based phase retrieval with the predictions of two quantum mechanical models. The first model, which was earlier employed in Ref.[24] to describe the ultrafast increase in conductivity of SiO 2 nanojunctions, is based on the nearestneighbor tight-binding approximation. The second model, presented in detail in Ref.[25], describes quantum dynamics in a one-dimensional pseudopotential (see the Methods Summary for details). In both models, the electric fi...

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“…If the spectrum between the two highest HCOs can be separated from the rest, i.e., spectrally filtered, only one half cycle contributes to the overall emission, resulting in an isolated attosecond pulse. HCO structures have also been exploited as a means to determine the wave form of the driving field on target [38][39][40]. In these experiments, simulated high-order-harmonic spectra were fitted to measured HCO traces, using the CEP, the chirp, and the peak intensity as fit parameters.…”

Section: A Half-cycle Cutoffsmentioning

confidence: 99%

Importance of intensity-to-phase coupling for water-window high-order-harmonic generation with few-cycle pulses

et al. 2015

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We present half-cycle cutoff features in the water window using high-order-harmonic generation (HHG) with two-cycle, carrier-envelope-phase-controlled pulses at 1.85 μm in a high-pressure neon target. A relative carrier-envelope-phase (CEP) shift of the acquired spectra at different pressures is related to an in situ slip of the CEP in the HHG target. A simple model based on the pressure-dependent dispersion of the target gas reveals the importance of the free electrons for this effect. Our analysis also reveals that the effect is relaxed at high target pressures due to plasma defocusing of the driving pulse. We show that as a consequence of the CEP slip mediated by free electrons, moderate-intensity fluctuations can have a detrimental influence on the generation and application of attosecond pulses. Our findings emphasize the potential of combining high target pressures and long driver wavelengths to reveal subtle details of the complex light-matter interaction of HHG.

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The generation and utilisation of half‐cycle cut‐offs in high harmonic spectra

Cited by 12 publications

References 74 publications

Generation of isolated attosecond pulses in the far field by spatial filtering with an intense few-cycle mid-infrared laser

Generation of isolated attosecond pulses in the far field by spatial filtering with an intense few-cycle mid-infrared laser

Solid-state light-phase detector

Importance of intensity-to-phase coupling for water-window high-order-harmonic generation with few-cycle pulses

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