Spectral Signature of Short Attosecond Pulse Trains

Mansten, Erik; Dahlström, Jan Marcus; Mauritsson, Johan; Ruchon, Thierry; L’Huillier, Anne; Tate, J.; Gaarde, Mette B.; Eckle, P.; Guandalini, A.; Holler, Mirko; Schapper, F.; Gallmann, L.; Keller, U.

doi:10.1103/physrevlett.102.083002

Cited by 30 publications

(33 citation statements)

References 22 publications

(31 reference statements)

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“…CEP-dependent effects in HHG have been observed in previous works [10,[12][13][14][15][16][17], but have often been limited to specific spectral regions, such as the cut-off [10,12,14] or the region between consecutive harmonic spectral peaks [15,16]. The interpretation of the observed CEP effects vary from quantum path interferences to interference between consecutive attosecond pulses.…”

Section: Introductionmentioning

confidence: 94%

“…The interpretation of the observed CEP effects vary from quantum path interferences to interference between consecutive attosecond pulses. In the latter case, several effects have been discussed: the number of interfering pulses [13], the variation of timing between these pulses as well as the phase difference between consecutive pulses. Here, we develop a simple model consisting in coherently adding the spectra from the number of emitted attosecond pulses, which is estimated to be three in the present experiment, taking into account the variation of the spectral phase with the laser CEP.…”

Section: Introductionmentioning

confidence: 99%

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Carrier-envelope phase dependent high-order harmonic generation with a high-repetition rate OPCPA-system

et al. 2015

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Abstract. We study high-order harmonic generation with a high-repetition rate (200 kHz), few-cycle, driving laser, based on optical parametric chirped pulse amplification. The system delivers carrier-envelope phase stable, 8 fs, 10 μJ pulses at a central wavelength of 890 nm. High-order harmonics, generated in a high-pressure Ar gas jet, exhibit a strong CEP-dependence over a large spectral range owing to excellent stability of the driving laser pulses. This range can be divided into three spectral regions with distinct CEP influence. The observed spectral interference structures are explained by an analytical model based upon multiple pulse interferences.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Carrier-envelope phase dependent high-order harmonic generation with a high-repetition rate OPCPA-system

et al. 2015

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“…Thus, in turn, the spatial and spectral features offer useful information on the HHG process [19,20] and the gas medium [21]. Moreover, each path has a specific excursion time and frequency property and it leads to a mapping between time and frequency for each harmonic [22] which has also been used to detect the nuclear dynamics [23].…”

Section: Introductionmentioning

confidence: 99%

Spectrally resolved spatiotemporal features of quantum paths in high-order-harmonic generation

Lan

Zhang

et al. 2015

Phys. Rev. A

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We experimentally disentangle the contributions of different quantum paths in high-order harmonic generation (HHG) from the spectrally and spatially resolved harmonic spectra. By adjusting the laser intensity and focusing position, we simultaneously observe the spectrum splitting, frequency shift and intensity-dependent modulation of harmonic yields both for the short and long paths. Based on the simulations, we discriminate the physical mechanisms of the intensity-dependent modulation of HHG due to the quantum path interference and macroscopic interference effects. Moreover, it is shown that the atomic dipole phases of different quantum paths are encoded in the frequency shift. In turn, it enables us to retrieve the atomic dipole phases and the temporal chirps of different quantum paths from the measured harmonic spectra. This result gives an informative mapping of spatiotemporal and spectral features of quantum paths in HHG.

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“…The harmonic spectrum is a consequence of the interference between these pulses. Similarly to the spatial interference effect discussed above, the spectral interference pattern depends on the relative phase Δφ t ¼ α q ðI a − I b Þ, which changes with CEP [30,31].…”

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confidence: 99%

Macroscopic Effects in Noncollinear High-Order Harmonic Generation

et al. 2014

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We study two-color high-order harmonic generation using an intense driving field and its weak second harmonic, crossed under a small angle in the focus. Employing sum-and difference-frequency generation processes, such a noncollinear scheme can be used to measure and control macroscopic phase matching effects by utilizing a geometrical phase mismatch component, which depends on the noncollinear angle. We further show how spatial phase effects in the generation volume are mapped out into the far field allowing a direct analogy with temporal carrier envelope effects in attosecond pulse generation. DOI: 10.1103/PhysRevLett.112.143902 PACS numbers: 42.65.Ky, 42.65.Re High-order harmonic generation (HHG) in gases using multicolor optical fields is becoming a common tool in attosecond science. Multicolor HHG has been implemented by mixing the fundamental field with waves at low harmonic [1][2][3] and at incommensurate [4,5] frequencies. Other schemes employ attosecond pulse trains mixed with the fundamental field [6] as well as synthesized light transients [7] for driving the HHG process. The control and flexibility brought about by using two or more driving fields is used, for example, to improve the efficiency of the generation process [3,8], to monitor the single atom response [9,10], and to implement gating techniques [11]. High-order wave mixing can further be beneficial for achieving phase matching [1,[12][13][14][15].Using multiple optical driving fields also allows for noncollinear geometries. This concept, used extensively in low-order frequency conversion processes such as optical parametric amplification, has barely been applied to attosecond science. In an early work, Birulin and co-workers [16] addressed theoretically the general concept of HHG in a noncollinear geometry. By mixing the fundamental and a weak second harmonic at an angle, Bertrand and co-workers [17] demonstrated the spatial separation of multiple extreme ultraviolet (XUV) beams corresponding to different sets of absorbed photon numbers from the two fields. A similar scheme was recently used [18] for reconstructing the spatiotemporal characteristics of the generated attosecond pulses. Other authors [19][20][21] concentrated on noncollinear sum-frequency generation (SFG) processes driven by two identical laser fields. Such a scheme allows for separation of the harmonics from the fundamental but suffers from phase matching problems.In this Letter, we theoretically and experimentally examine the influence of noncollinear geometries in HHG, analyzing in detail the macroscopic aspects. We show for the first time, to our knowledge, how a weak noncollinear field can be used as a probe to monitor and control phase matching. We show that difference-frequency generation (DFG), where a photon (or several photons) is emitted in the conversion process, is in general more favorable than SFG [22], which becomes very inefficient with increasing noncollinear angle. This leads to the counterintuitive result that the XUV radiation is dominantly emitted ou...

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Spectral Signature of Short Attosecond Pulse Trains

Cited by 30 publications

References 22 publications

Carrier-envelope phase dependent high-order harmonic generation with a high-repetition rate OPCPA-system

Carrier-envelope phase dependent high-order harmonic generation with a high-repetition rate OPCPA-system

Spectrally resolved spatiotemporal features of quantum paths in high-order-harmonic generation

Macroscopic Effects in Noncollinear High-Order Harmonic Generation

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