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We employ the two-band density-matrix equations and time-dependent density functional theory to calculate high-order harmonic generation (HOHG) in graphene under a femtosecond laser irradiation. Our investigation uncovers a striking…

Atomic Physics · Physics 2023-07-25 Fulong Dong , Qinzhi Xia , Jie Liu

The generation of harmonics by atoms or ions in a two-color, coplanar field configuration with commensurate frequencies is investigated through both, an analytical calculation based on the Lewenstein model and the numerical ab initio…

Atomic Physics · Physics 2009-11-07 F. Ceccherini , D. Bauer , F. Cornolti

Recent studies have shown convolutional neural networks (CNNs) can be trained to perform modal decomposition using intensity images of optical fields. A fundamental limitation of these techniques is that the modal phases can not be uniquely…

Optics · Physics 2021-04-20 Mitchell G. Schiworski , Daniel D. Brown , David J. Ottaway

We propose a new scheme to generate high-brightness and temporal coherent soft x-ray radiation in a seeded free-electron laser. The proposed scheme is based the coherent harmonic generation (CHG) and superradiant principles. A CHG scheme is…

Accelerator Physics · Physics 2016-09-06 Kaishang Zhou , Chao Feng , Haixiao Deng , Dong Wang

Employing deep neural networks for Hyperspectral remote sensing (HSRS) image classification is a challenging task. HSRS images have high dimensionality and a large number of channels with substantial redundancy between channels. In…

Computer Vision and Pattern Recognition · Computer Science 2023-08-09 Mohammad Joshaghani , Amirabbas Davari , Faezeh Nejati Hatamian , Andreas Maier , Christian Riess

We describe an approach based on topology optimization that enables automatic discovery of wavelength-scale photonic structures for achieving high-efficiency second-harmonic generation (SHG). A key distinction from previous formulation and…

Echo-enabled harmonic generation free-electron lasers (EEHG FELs) are promising candidates to produce fully coherent soft x-ray pulses by virtue of efficient high harmonic frequency up-conversion from UV lasers. The ultimate spectral limit…

We report here on results of experimental-theoretical investigation of high-order harmonic generation (HHG) in layers of CdSe semiconductor quantum dots of different sizes and a reference bulk CdSe thin film. We observe a strong decrease in…

Diffractive neural networks (DNNs) are an emerging approach for the realization of photonic artificial intelligence, especially due to their suitability for machine-vision applications and high-dimensional photonic information processing at…

Optics · Physics 2026-03-27 Marie Braasch , Anna Kartashova , Elena Goi , Thomas Pertsch , Sina Saravi

High-order harmonic generation (HHG) from molecular ion HeH$^{2+}$ in two initial states of $1s\sigma$ (ground state) and $2p\sigma$ (first excited state) is investigated theoretically, in homogeneous and plasmonic-enhanced laser fields.…

Atomic Physics · Physics 2018-07-04 Nehzat Safaei

The majority of sources of coherent optical radiation rely on laser oscillators driven by population inversion. Despite their technological importance in communications, medicine, industry, and other fields, it remains a challenge to access…

Optics · Physics 2021-10-22 Lamia Ateshian , Hyeongrak Choi , Mikkel Heuck , Dirk Englund

Computer-generated holography (CGH) is a promising method that modulates user-defined waveforms with digital holograms. An efficient and fast pipeline framework is proposed to synthesize CGH using initial point cloud and MRI data. This…

Computer Vision and Pattern Recognition · Computer Science 2025-08-12 Justin London

Atomic clusters presents an isolated system that models the bulk materials whose mechanism of HHG remains uncertain, and a promising medium to produce HHG beyond the limited conversion efficiency for gaseous atoms. Here we reveal that the…

Optics · Physics 2016-06-07 Na Li , Peng Liu , Ya Bai , Peng Peng , Ruxin Li , Zhizhan Xu

We perform a detailed analysis of high-order harmonic generation (HHG) in atoms within the strong field approximation (SFA) by considering spatially inhomogeneous monochromatic laser fields. We investigate how the individual pairs of…

Atomic Physics · Physics 2015-06-05 T. Shaaran , M. F. Ciappina , M. Lewenstein

Applying time-dependent local density approximation (TDLDA), we study the high-order harmonic generation (HHG) of ethylene subjected to the one-color ($\omega=2.72$ eV) and the two-color ($\omega_1=2.72$ eV and $\omega_2=5.44$ eV)…

Atomic and Molecular Clusters · Physics 2009-03-31 Z. P. Wang , P. M. Dinh , P. -G. Reinhard , E. Suraud , F. S. Zhang

An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results…

When a laser pulse impinges on a molecule which is invariant under certain symmetry operations selection rules for harmonic generation (HG) arise. In other words: symmetry controls which channels are open for the deposition and emission of…

Atomic Physics · Physics 2009-11-07 D. Bauer , F. Ceccherini

The generation of harmonic radiation through a non-linear mechanism driven by bunching at fundamental frequency is an important option in the operation of high gain Free-Electron Lasers (FELs). The use of harmonic generation at a large…

Accelerator Physics · Physics 2016-09-08 Gianluca Geloni , Evgeni Saldin , Evgeni Schneidmiller , Mikhail Yurkov

We consider harmonics generation and wave-mixing by two-color multi photon resonant excitation of three-level atoms/molecules in strong laser fields. The coherent part of the spectra corresponding to multicolor harmonics generation is…

Atomic Physics · Physics 2016-08-24 H. K. Avetissian , B. R. Avchyan , G. F. Mkrtchian

High-order harmonic generation (HHG) in solids - the frequency up-conversion of an optical signal - is governed by symmetries. At terahertz (THz) frequencies, HHG is a key technology to access high frequency spectral windows that are…