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 report on the observation of enhanced high harmonics from a carbon plasma using sub-5-fs laser pulses, which can be attributed to the presence of carbon nanoparticles in the ablation plumes.
Abstract: We report on the observation of enhanced high harmonics from a carbon plasma using sub-5-fs laser pulses. The efficiency of harmonic generation in the range of 14\char21{}25 eV was up to five times higher in the case of a plasma medium (graphite ablation) compared with gas (argon) under similar experimental conditions. The harmonic enhancement can be attributed to the presence of carbon nanoparticles in the ablation plumes.
57 citations
TL;DR: In this article, the influence of the personal computer processing mode on the generation of line current harmonics has been investigated using a university library building containing over 370 PCs, and the harmonics were monitored from the building switchboard using purpose-designed hardware.
Abstract: The influence of the personal computer processing mode on the generation of line current harmonics has been investigated using a university library building containing over 370 PCs. The harmonics were monitored from the building switchboard using purpose-designed hardware. The PCs were set to execute four types of processing mode: idle, numerical processing, floppy, and hard disk accesses. The results recorded were indicative of harmonics caused by the PC box only, and secondary effects of harmonic production caused by distorted supply voltages were avoided. The results show that hard disk accesses cause the highest level of harmonic production affecting the 3rd and 5th components. Harmonic attenuation was very apparent when comparing the results between a single PC and 124 PCs connected to the same supply phase. However, attenuation and diversity effects due to changes in loading level on the PC power supply were not as predicted, showing an increase in harmonic generation with line current RMS level.
57 citations
TL;DR: In this article, it was shown from x-ray diffraction analyses, micro-Raman-scattering spectra and second-harmonic generation measurements that the crystal structure of Sm2(MoO4)3 formed by the crystallization is the β′-phase structure with an orthorhombic (noncentrosymmetric) symmetry.
Abstract: Some glasses such as 21.25Sm2O3.63.75MoO3.15B2O3 (mol %) giving the formation of nonlinear optical Sm2(MoO4)3 crystals through conventional crystallization in an electric furnace and through continuous-wave Nd: yttrium aluminum garnet (YAG) laser (wavelength: 1064nm) irradiation (samarium atom heat processing) have been developed. It is proposed from x-ray diffraction analyses, micro-Raman-scattering spectra, and second-harmonic generation measurements that the crystal structure of Sm2(MoO4)3 formed by the crystallization is the β′-phase structure with an orthorhombic (noncentrosymmetric) symmetry. The lines consisting of nonlinear optical β′-Sm2(MoO4)3 crystals are written at the surface of glasses by YAG laser irradiation (laser power: P=0.4W, laser scanning speed: S=1–10μm∕s), and, in particular, homogeneous crystal lines are formed at the laser scanning speed of 1μm∕s. Refractive index changes (not crystallization) are also induced by YAG laser irradiation of P=0.4W and a high laser scanning speed of ...
57 citations
TL;DR: An ab initio quantum study of the near- and below-threshold harmonic generation of caesium atoms in an intense 3,600-nm mid-infrared laser field finds that the multiphoton-dominated trajectories only involve the electrons scattered off the higher part of the combined atom-field potential followed by the absorption of many photons in near-and below-Threshold regime.
Abstract: Near- and below-threshold harmonic generation provides a potential approach to generate vacuum-ultraviolet frequency comb. However, the dynamical origin of in these lower harmonics is less understood and largely unexplored. Here we perform an ab initio quantum study of the near- and below-threshold harmonic generation of caesium (Cs) atoms in an intense 3,600-nm mid-infrared laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, the roles of multiphoton and multiple rescattering trajectories on the near- and below-threshold harmonic generation processes are clarified. We find that the multiphoton-dominated trajectories only involve the electrons scattered off the higher part of the combined atom-field potential followed by the absorption of many photons in near- and below-threshold regime. Furthermore, only the near-resonant below-threshold harmonic is exclusive to exhibit phase locked features. Our results shed light on the dynamic origin of the near- and below-threshold harmonic generation.
57 citations
TL;DR: In this article, the direction of laser polarization with respect to the molecular axis of a linear molecule can have a significant effect on high-harmonic generation and the efficiency of some high harmonics can be higher by up to three orders of magnitude when the laser is polarized in the perpendicular direction rather than parallel to a molecular axis.
Abstract: We show that the direction of laser polarization with respect to the molecular axis of a linear molecule can have a significant effect on high-harmonic generation. Numerical integration of the two-dimensional Schrodinger equation of the H2+ and the H32+ model molecular ions shows that the efficiency of some high harmonics can be higher by up to three orders of magnitude when the laser is polarized in the perpendicular direction rather than parallel to the molecular axis. We discuss experiments to test this prediction.
57 citations