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High harmonic generation

About: High harmonic generation is a research topic. Over the lifetime, 11694 publications have been published within this topic receiving 222650 citations. The topic is also known as: HHG.


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Journal ArticleDOI
TL;DR: The present findings provide a microscopic understanding of the large SHG susceptibility in 2D group IV monochalcogenide multiferroics from first-principles theory and open up a variety of new avenues for 2D ferroelectrics, multiferraics, and nonlinear optoelectronics.
Abstract: Nonlinear optical properties of materials such as second and higher order harmonic generation and electro-optic effect play pivotal roles in lasers, frequency conversion, electro-optic modulators, switches, and so forth. The strength of nonlinear optical responses highly depends on intrinsic crystal symmetry, transition dipole moments, specific optical excitation, and local environment. Using first-principles electronic structure theory, here we predict giant second harmonic generation (SHG) in recently discovered two-dimensional (2D) ferroelectric–ferroelastic multiferroics–group IV monochalcogenides (i.e., GeSe, GeS, SnSe, and SnS). Remarkably, the strength of SHG susceptibility in GeSe and SnSe monolayers is more than 1 order of magnitude higher than that in monolayer MoS2, and 2 orders of magnitude higher than that in monolayer hexagonal BN. Their extraordinary SHG is dominated by the large residual of two opposite intraband contributions in the SHG susceptibility. More importantly, the SHG polarizati...

140 citations

Journal ArticleDOI
TL;DR: When fully antisymmetrized multielectron wave functions and electronic relaxation in the cation are considered, molecular orbital tomography records the image of the Dyson orbital plus exchange contributions from inner shells, which can be interpreted as a complete Hartree-Fock wave function.
Abstract: It was recently shown that the highest molecular orbital of ${\mathrm{N}}_{2}$ could be reconstructed from a series of high harmonic measurements. Existing theories of high harmonic generation and orbital tomographic imaging are based on the single active electron approximation that ignores essential quantum mechanical properties such as the indistinguishability of identical particles and the Pauli exclusion principle. We show that, when fully antisymmetrized multielectron wave functions and electronic relaxation in the cation are considered, molecular orbital tomography records the image of the Dyson orbital plus exchange contributions from inner shells. The mixing of contributions from more than one molecular orbital gives access to additional wave function information. By utilizing the exchange term, harmonic emission from a closed-shell 4-electron system can be interpreted as a complete Hartree-Fock wave function.

138 citations

Journal ArticleDOI
TL;DR: High-order harmonic emission from He+ is enhanced by many orders of magnitude compared with the case of the fundamental pulse alone and its combined pulse leads to a surprisingly high He2+ yield of 17%.
Abstract: We theoretically study the response of He+ exposed simultaneously to an intense Ti:sapphire laser and its 27th or 13th harmonic pulses. High-order harmonic emission from He+ is enhanced by many orders of magnitude compared with the case of the fundamental pulse alone. Moreover, while an individual 10 fs laser (wavelength lambda(F)=800 nm) or its 27th harmonic pulse with a peak intensity of 3 x 10(14) and 10(13) W/cm(2), respectively, ionizes no more than 5 x 10(-6) of He+, their combined pulse leads to a surprisingly high He2+ yield of 17%.

138 citations

Journal ArticleDOI
TL;DR: In this paper, a theory of multiple-photon excitation of an electron from the valence to the conduction in a solid is developed, and the experimental conditions for observing such transitions are considered; presently available optical maser sources of radiation are of sufficient intensity to enable doublequantum processes to be experimentally observable in semiconductors and insulators.
Abstract: A number of possible nonlinear light effects in solids are discussed where the optical properties of a medium depend upon the value of the incident $E$ and $H$ radiation field; as a consequence of the nonlinear properties of these effects and their intrinsic fast response times, the possibility exists of producing harmonic generation and mixing at infrared and visible frequencies. The theory of multiple-photon excitation of an electron from the valence to the conduction in a solid is developed. It is shown that this process exhibits an intensity-dependent absorption edge at photon energies below the minimal energy gap of a solid. The experimental conditions for observing such transitions are considered; presently available optical maser sources of radiation are of sufficient intensity to enable double-quantum processes to be experimentally observable in semiconductors and insulators.

138 citations

Journal ArticleDOI
TL;DR: A new technique is reported, whereby the spectral phase of the attosecond pulse is extracted from the oscillation component with the dressing laser frequency in the photoelectron spectrogram, termed PROOF (Phase Retrieval by Omega Oscillation Filtering), which can be applied to characterizing attoseCond pulses with ultrabroad bandwidths.
Abstract: Recent progress in sub-laser-cycle gating of high-order harmonic generation promises to push the limits on optical pulse durations below the atomic unit of time, 24 as, which corresponds to a bandwidth broader than 75 eV. However, the available techniques for attosecond pulse measurement are valid only for narrow-bandwidth spectra, due to one of the key approximations made in the phase retrieval. Here we report a new technique for characterizing attosecond pulses, whereby the spectral phase of the attosecond pulse is extracted from the oscillation component with the dressing laser frequency in the photoelectron spectrogram. This technique, termed PROOF (Phase Retrieval by Omega Oscillation Filtering), can be applied to characterizing attosecond pulses with ultrabroad bandwidths.

138 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023177
2022438
2021399
2020489
2019516
2018433