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, a fast drop of the second-harmonic intensity and the Kerr-signal within 300 fs after optical excitation has been observed which is followed by a partial recovery within a few picoseconds.
Abstract: Relaxation processes on the picosecond and subpicosecond time scale after optical excitation have been studied by time-resolved magnetization-induced second-harmonic generation from ferromagnetic nickel. A fast drop of the second-harmonic intensity and the Kerr-signal within 300 fs after optical excitation has been observed which is followed by a partial recovery within a few picoseconds. We show that the fast initial drop cannot be unambiguously attributed to an ultrafast decrease of the magnetization.
88 citations
TL;DR: In this article, high-order optical harmonics were generated from solid targets using laser pulses of 35 and 120 femtoseconds, and high conversion efficiency was achieved, e.g., ${10}^{\ensuremath{-}6} to the $10\mathrm{th}$ harmonic.
Abstract: This paper discusses the generation of high-order optical harmonics from solid targets using laser pulses of 35 and 120 femtoseconds. Harmonics up to the 35th order were observed. High conversion efficiency has been achieved, e.g., ${10}^{\ensuremath{-}6}$ to the $10\mathrm{th}$ harmonic. It is demonstrated that the harmonic emission is highly directional and that the harmonic efficiency decreases rapidly with increasing plasma scale length.
88 citations
TL;DR: A robust scheme to select a single high-order harmonic among the harmonic comb by using a driving laser field with subcycle waveform control, which is synthesized by the fundamental 800 nm laser pulse and two controlling laser pulses at 400 and 267 nm with perpendicular polarizations is experimentally demonstrated.
Abstract: We experimentally demonstrate a robust scheme to select a single high-order harmonic among the harmonic comb by using a driving laser field with subcycle waveform control, which is synthesized by the fundamental 800 nm laser pulse and two controlling laser pulses at 400 and 267 nm with perpendicular polarizations. By controlling the relative phase among the pulses of different colors, a single high-order harmonic is selectively enhanced while the adjacent harmonics are greatly suppressed with the intensity contrast increased by more than 1 order of magnitude and the peak intensity enhanced simultaneously by more than 2 orders of magnitude compared to the case by using only the fundamental 800 nm laser pulse. Such phenomena can be mainly attributed to the intra-atomic phase matching realized with the sub-cycle waveform controlled field.
88 citations
TL;DR: It is demonstrated that focusing of the soft-x-ray beam to a 1-microm spot size with a peak intensity of 1 x 10(14) W/cm2, which is to this knowledge the highest ever reported in the Soft X-ray region.
Abstract: We investigate the focusability of intense coherent soft-x-ray radiation generated by high-order harmonic conversion. The 27th-harmonic wave at 29.6 nm is focused by an off-axis parabolic mirror with a SiC/Mg multilayer coating. Focal-spot images are observed from the visible fluorescence induced by the soft-x-ray photons on a Ce:YAG scintillator. We demonstrate focusing of the soft-x-ray beam to a 1-microm spot size with a peak intensity of 1 x 10(14) W/cm2, which is to our knowledge the highest ever reported in the soft-x-ray region.
88 citations
TL;DR: In this article, a wave flume was used to study the differences between harmonic evolution of monochromatic waves as they propagate over a submerged impermeable or porous step under non-breaking conditions.
88 citations