Generation of High Order Harmonics from Solid Surfaces by Intense Femtosecond Laser Pulses

Linde, D. von der; Engers, T.; Jenke, G.; Agostini, Pierre; Grillon, G.; Nibbering, Erik T. J.; Chambaret, J. P.; Curley, P. F.; Mysyrowicz, A.; Antonetti, A.

doi:10.1007/978-1-4615-5897-2_72

Cited by 12 publications

(12 citation statements)

References 6 publications

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“…The quantum opto-electronic response of metals is dominantly coherent, as manifested by specular reflection of light, yet large bandwidths and ultrafast phase relaxation processes of the many-body electronic system impede its time-resolved spectroscopic investigation [1][2][3][4][5]. The coherent responses of metals are evident in highly nonlinear optical interactions like above-threshold multiphoton photoemission [6][7][8][9][10] and high-harmonic generation [11,12]. Such processes epitomize the strong-field, attosecond physics of atomic or molecular gases, as well as electron emission from nanostructured metal tips [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces

Reutzel

Petek

2019

Phys. Rev. X

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Light interacting with metals elicits an ultrafast coherent many-body screening response on sub-to few-femtosecond time-scales, which makes its experimental observation challenging. Here, we describe the coherent two-dimensional (2D) multi-photon photoemission study of the Shockley surface state (SS) of Ag(111) as a benchmark for spectroscopy of the coherent nonlinear response of metals to an optical field in the perturbative regime. Employing interferometrically time-resolved multi-photon photoemission spectroscopy (ITR-mPP), we correlate the coherent polarizations and populations excited in the sample with final photoelectron distributions where the interaction terminates. By measuring the non-resonant 3-and 4-photon photoemission of the SS state, as well as its replica structures in the above-threshold photoemission (ATP), we record the coherent response of the Ag(111) surface by 2D photoemission spectroscopy and relate it to its band structure. We interpret the mPP process by an optical Bloch equation (OBE) model, which reproduces the main features of the surface state coherent polarization dynamics recorded in ITR-mPP experiments: The spectroscopic components of the 2D photoelectron spectra are shown to depend on the nonlinear orders of the coherent photoemission process m as well as on the induced coherence n.

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Section: Introductionmentioning

confidence: 99%

Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces

Reutzel

Petek

2019

Phys. Rev. X

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“…For example, ultrashort pulses may be frequency up-converted into UV, soft and hard x-ray sources through harmonic generation. 1,2 Similarly, intense ultrashort pulses incident on solid targets can ionize inner-shell electrons, resulting in Kα fluorescence line radiation. 3 In addition to short wavelength generation phenomena, ultrashort pulses can also be frequency down-converted to mid-infrared wavelengths through the nonlinear processes of optical parametric amplification, 4 difference frequency generation, 5 and optical rectification.…”

Section: Introductionmentioning

confidence: 99%

Plasma enhancement of femtosecond laser-induced electromagnetic pulses at metal and dielectric surfaces

et al. 2014

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Abstract. In a previous report, we have shown that the long wavelength, electromagnetic-pulsed (EMP) energy generated by ultrashort (38 fs) laser pulse ablation of a metal target is enhanced by an order of magnitude due to a preplasma generated by a different, 14-ns-long laser pulse. Here, we further investigate this EMP enhancement effect in a 2-to 16-GHz microwave region with different target materials and laser parameters. Specifically, we show a greater than two orders of magnitude enhancement to the EMP energy when the nanosecond and ultrashort laser pulses are coincident on a glass target, and greater than one order of magnitude enhancement when the pulses are coincident on a copper target.

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“…Therefore, the field cannot be thought of as a small perturbation to the crystal. The non-perturbative HHG from bulk crystals has been considered theoretically 12-14 but has never been observed experimentally until now.Previously, experimental observation of non-perturbative HHG in solids was only in reflection geometry [15][16][17][18] perturbative harmonics below the band edge up to the seventh order were produced by exciting semiconducting ZnSe with a maximum field strength of ∼0.08 V Å −1 at a central wavelength of 3.9 µm (ref. 19).…”

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confidence: 99%

Observation of high-order harmonic generation in a bulk crystal

et al. 2010

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Harmonic generation is a general feature of driven nonlinear systems. In particular high-order harmonic generation (HHG) in atomic gases 1 is the basis for producing attosecond pulses 2,3 . In molecules and clusters, the existence of multiple ionization and recombination sites makes for richer dynamics allowing imaging of molecular orbitals 4,5 , higher conversion efficiency 6 and the possibility of extending the high-energy cutoff 7 . In the strong-field limit, HHG in bulk crystals is fundamentally different from that in the atomic case owing to the high density and periodic structure. Here we present the first observation of HHG in a bulk crystalline solid using a long-wavelength few-cycle laser. The harmonics spectra extend well beyond the band edge of the ZnO crystal, show a clear non-perturbative character and exhibit a cutoff that scales linearly with the electric field of the drive laser. Our results have important implications for the understanding of attosecond electron dynamics and other non-equilibrium band-structure-related phenomena in strongly driven bulk solids.The HHG spectrum from a gas typically comprises a region of rapidly decreasing low orders that scale perturbatively followed by a slowly varying succession of higher orders that scale nonperturbatively with the strength of the drive laser 1 . At the tunnelling limit of strong-field ionization 8 , the non-perturbative harmonic generation process has been described semiclassically in a recollision model 9,10 consisting of three steps: tunnel ionization of an electron, its acceleration in the laser field, and its recombination to the parent ion with an energy release in the form of higher-energy photons-a coherent process that occurs on successive half-cycles of the laser pulse, leading to emission of odd harmonics. The single-atom maximum photon energy is 9,11h ω max = I p + 3.2U p , where I p is the ionization potential and U p = e 2 E 2 λ 2 /16π 2 mc 2 is the ponderomotive energy of the electron in the laser field. The amplitude of the maximum excursion of a recolliding electron is r max = eEλ 2 /4π 2 mc 2 . For the conditions of our experiments, E = 0.6 V Å −1 at λ = 3.25 µm, the atomic case would be U p = 5 eV and r max = 32 Å. The latter is many times the lattice constant of a typical crystal. Thus, we expect the possibility of ionization from one site and recombination on another; however, because of the lattice periodicity the process would still be coherent. We note that at this field strength, the potential across a lattice constant is comparable to the bandgap of a typical insulator. Therefore, the field cannot be thought of as a small perturbation to the crystal. The non-perturbative HHG from bulk crystals has been considered theoretically 12-14 but has never been observed experimentally until now.Previously, experimental observation of non-perturbative HHG in solids was only in reflection geometry [15][16][17][18] perturbative harmonics below the band edge up to the seventh order were produced by exciting semiconducting ZnSe with...

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Generation of High Order Harmonics from Solid Surfaces by Intense Femtosecond Laser Pulses

Cited by 12 publications

References 6 publications

Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces

Coherent Two-Dimensional Multiphoton Photoelectron Spectroscopy of Metal Surfaces

Plasma enhancement of femtosecond laser-induced electromagnetic pulses at metal and dielectric surfaces

Observation of high-order harmonic generation in a bulk crystal

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