Enhanced high-order harmonic generation in donor-doped band-gap materials

Yu, Chuan; Hansen, Kenneth K.; Madsen, Lars Bojer

doi:10.1103/physreva.99.013435

Cited by 65 publications

(65 citation statements)

References 47 publications

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“…[16] for a modern introduction into the topological aspects of the SSH model). Figure 1 illustrates the connection between the modelling using the very simple SSH tight-binding approach (leading to two bands only) [16,41,42,44] and the abinitio density-functional theory (DFT) on a fine-grained position-space grid [28,31,[45][46][47]. Let us first consider the upper panel.…”

Section: Introductionmentioning

confidence: 99%

“…The atoms are shifted from their equidistant positions (lattice constant a) alternatingly by δ to the right and left, generating the two possible dimerizations called phase A and phase B. For the case of one electron per ion, the equidistant configuration is metallic (half populated lowest band) but energetically less favor- Connection between atom positions on a finegrained, real-space grid as used in DFT [28,31,[45][46][47] and the SSH model [16,41,42] to illustrate the discussion in the Introduction.…”

Section: Introductionmentioning

confidence: 99%

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High-harmonic generation in Su-Schrieffer-Heeger chains

Jürß

Bauer

2019

Phys. Rev. B

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Su-Schrieffer-Heeger (SSH) chains are the simplest model systems that display topological edge states. We calculate high-harmonic spectra of SSH chains that are coupled to an external laser field of a frequency much smaller than the band gap. We find huge differences between the harmonic yield for the two topological phases, similar to recent results obtained with more demanding timedependent density functional calculations [D. Bauer, K.K. Hansen, Phys. Rev. Lett. 120, 177401 (2018)]. This shows that the tight-binding SSH model captures the essential topological aspects of the laser-chain interaction (while higher harmonics involving higher bands or screening in the metal phase are absent). We study the robustness of the topological difference with respect to disorder, a continuous phase transition in position space, and on-site potentials. Further, we address the question whether the edges need to be illuminated by the laser for the huge difference in the harmonic spectra to be present. arXiv:1902.04120v2 [physics.optics]

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-harmonic generation in Su-Schrieffer-Heeger chains

Jürß

Bauer

2019

Phys. Rev. B

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“…The last decade has seen the emergence of highharmonic generation (HHG) in solids [1][2][3][4][5][6] as a promising and compact ultrafast light source, as well as a potential tool to reconstruct crystal band structures [7], measure Berry curvatures [8,9], and probe topological phase transitions [10][11][12]. Complementing experimental progress, a number of theoretical studies have explored HHG in solids either in terms of reciprocal-space dynamics within the band structure [1,5,6,[13][14][15][16][17][18][19][20][21][22][23], which contains both intra-and interband contributions, or in terms of realspace particle-like dynamics in the crystal [2,3,14,[24][25][26][27][28][29].…”

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confidence: 99%

“…We found that the spatial width of the electron and hole wave packets can be almost one order of magnitude larger than the lattice constant, allowing for the imperfect recollisions. This suggests that the harmonic emission can probe the degree of spatial homogeneity of the periodic structure [25,39,[53][54][55] as well as the temporal dephasing introduced by e.g. electron correlation.…”

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confidence: 99%

Imperfect Recollisions in High-Harmonic Generation in Solids

2020

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We theoretically investigate high-harmonic generation in hexagonal boron nitride with linearly polarized laser pulses. We show that imperfect recollisions between electron-hole pairs in the crystal give rise to an electron-hole-pair polarization energy that leads to a double-peak structure in the subcycle emission profiles. An extended recollision model (ERM) is developed that allows for such imperfect recollisions, as well as effects related to Berry connections, Berry curvatures, and transition-dipole phases. The ERM illuminates the distinct spectrotemporal characteristics of harmonics emitted parallel and perpendicularly to the laser polarization direction. Imperfect recollisions are a general phenomenon and a manifestation of the spatially delocalized nature of the real-space wave packet, they arise naturally in systems with large Berry curvatures, or in any system driven by elliptically polarized light.

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“…By introducing dopants, we can alter the electronic structure and change the non-linear optical properties of the crystal. This could be used to tailor certain materials for strong field optoelectronics applications, for example a new degree of control in solid-state high harmonics [17].…”

Section: Introductionmentioning

confidence: 99%

Controlling the non-linear optical properties of MgO by tailoring the electronic structure

et al. 2020

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The study of the non-linear response of matter to high electric fields has recently encompassed harmonic generation in solids at near-infrared (NIR) driving wavelengths. Interest has been driven by the prospect of ultrafast signal processing and all-optical mapping of electron wavefunctions in solids. Engineering solid-state band structures to control the non-linear process has already been highlighted theoretically. Here, we show experimentally for the first time that second harmonic generation (SHG) can be enhanced by doping crystals of magnesium oxide (MgO) with chromium (Cr) atoms. We show that the degree of enhancement depends nonlinearly on dopant concentration. The SHG efficiency is shown to increase when Cr dopants are introduced into pure MgO. A physical picture of the effect of Cr dopants is aided by density functional theory (DFT) calculations of the electronic structure for pure and doped samples. This work shows an unambiguous enhancement of the SHG efficiency by modifying the electronic structure. The observed effects are consistent with an electronic structure that facilitates the surface induced SHG and demonstrates a minimal angular dependence. This work highlights the potential of manipulating the electronic structure of solids to control or test theories of their non-linear optical response.

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Enhanced high-order harmonic generation in donor-doped band-gap materials

Cited by 65 publications

References 47 publications

High-harmonic generation in Su-Schrieffer-Heeger chains

High-harmonic generation in Su-Schrieffer-Heeger chains

Imperfect Recollisions in High-Harmonic Generation in Solids

Controlling the non-linear optical properties of MgO by tailoring the electronic structure

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