Topic
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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TL;DR: In this paper, the authors present ab initio quantum and classical investigations on the production and control of a single attosecond pulse by using few-cycle intense laser pulses as the driving field.
Abstract: We present ab initio quantum and classical investigations on the production and control of a single attosecond pulse by using few-cycle intense laser pulses as the driving field. The high-harmonic-generation power spectrum is calculated by accurately and efficiently solving the time-dependent Schr\"odinger equation using the time-dependent generalized pseudospectral method. The time-frequency characteristics of the attosecond xuv pulse are analyzed in detail by means of the wavelet transform of the time-dependent induced dipole. To better understand the physical processes, we also perform classical trajectory simulation of the strong-field electron dynamics and electron returning energy map. We found that the quantum and classical results provide complementary and consistent information regarding the underlying mechanisms responsible for the production of the coherent attosecond pulse. For few-cycle $(5\phantom{\rule{0.3em}{0ex}}\mathrm{fs})$ driving pulses, it is shown that the emission of the consecutive harmonics in the supercontinuum cutoff regime can be synchronized and locked in phase resulting in the production of a coherent attosecond pulse. Moreover, the time profile of the attosecond pulses can be controlled by tuning the carrier envelope phase.
104 citations
13 Jan 2016
TL;DR: In this article, the scaling principle of nonlinear light-matter interaction in gases was identified and it was shown that paraxial nonlinear wave equations are scale invariant if spatial dimensions, gas density, and laser pulse energy are scaled appropriately.
Abstract: Nonlinear optical methods have become ubiquitous in many scientific areas, from fundamental studies of time-resolved electron dynamics to microscopy and spectroscopy applications. They are, however, often limited to a certain range of parameters such as pulse energy and average power. Restrictions arise from, for example, the required field intensity as well as from parasitic nonlinear effects and saturation mechanisms. Here, we identify a fundamental principle of nonlinear light–matter interaction in gases and show that paraxial nonlinear wave equations are scale-invariant if spatial dimensions, gas density, and laser pulse energy are scaled appropriately. As an example, we apply this principle to high-order harmonic generation and provide a general method for increasing peak and average power of attosecond sources. In addition, we experimentally demonstrate the implications for the compression of short laser pulses. Our scaling principle extends well beyond those examples and includes many nonlinear processes with applications in different areas of science.
104 citations
TL;DR: Measurements reveal that, for the conditions optimum for harmonic generation, the orientation is produced by preferential ionization which depletes the sample of molecules of one orientation.
Abstract: We produce oriented rotational wave packets in CO and measure their characteristics via high harmonic generation. The wave packet is created using an intense, femtosecond laser pulse and its second harmonic. A delayed 800 nm pulse probes the wave packet, generating even-order high harmonics that arise from the broken symmetry induced by the orientation dynamics. The even-order harmonic radiation that we measure appears on a zero background, enabling us to accurately follow the temporal evolution of the wave packet. Our measurements reveal that, for the conditions optimum for harmonic generation, the orientation is produced by preferential ionization which depletes the sample of molecules of one orientation.
104 citations
TL;DR: Frolov et al. as discussed by the authors proposed a closed-form analytic formula for high-order harmonic generation (HHG) rates for atoms, which generalizes an HHG formula for negative ions.
Abstract: A closed-form analytic formula for high-order harmonic generation (HHG) rates for atoms (that generalizes an HHG formula for negative ions [M. V. Frolov, J. Phys. B 42, 035601 (2009)10.1088/0953-4075/42/3/035601]) is used to study laser wavelength scaling of the HHG yield for harmonic energies in the cutoff region of the HHG plateau. We predict increases of the harmonic power for HHG by Ar, Kr, and Xe with increasing wavelength lambda over atom-specific intervals of lambda in the infrared region, lambda approximately (0.8-2.0) microm.
104 citations
17 Jun 2007
TL;DR: High-order harmonic emission is observed in acetylene and allene molecules with 14 fs laser pulses producing a time dependent modulation of the harmonic signal as the ensemble undergoes the subsequent alignment revivals.
Abstract: Laser driven high-order harmonic generation (HHG) from molecules depends on the particular symmetry of the highest occupied molecular orbital (HOMO) and its orientation with respect to the laser field. High-order harmonic emission is observed in acetylene and allene molecules with 14 fs laser pulses. The molecules are aligned non-adiabatically producing a time dependent modulation of the harmonic signal as the ensemble undergoes the subsequent alignment revivals. At the points of maximum alignment the harmonic signal is measured as a function of the alignment angle showing a behavior that can be related to the structure of the highest occupied molecular orbitals.
103 citations