Quasi-phase-matching by metallic nanostructures for high-harmonics generation and stimulated Raman scattering
Final Report Abstract
High harmonic generation is an optical process by which visible light (pump beam) is converted into x-ray. Previously, it was proposed to use metal nanoparticle to assist this process. This allows to reduce the required light intensity, however, the efficiency of conversion becomes low. In this project, possibility to increase the conversion efficiency are investigated. The reason for low efficiency is that x-ray radiation emitted from different positions along the pump beam show destructive interference, i.e., cancel each other out. The central idea of this project is to place the nanoparticles at specific positions, so that the contributions form each nanopartice enhance each other. We investigate three setups to achieve such placement. First one is to modulate the density of nanoparticles in a mixture of nanopartices and gas. Second one is to use a thin hollow waveguide and to modulate its inner radius. Third possibility is to use predeposited stripes of metal on a surface, ablate this metal, and then use the resulting periodically-modulated density of metal nanoparticles. As a result, an increase of efficiency by a factor up to 200 is predicted. In the second part of this project, periodically modulated Raman-active medium was investigated. It is predicted that output radiation has a very narrow spectrum when using high-power pump beam and high pressure of gas. The reason is that thermal motion of molecules, which results in disadvantageous Doppler effect, is almost stopped. The results of the project can find applications in creating new efficient sources of the x-ray radiation and in highresolution spectroscopy. While it was expected that high-power pumping of Raman-active gas will result in efficient spectral broadening, a dramatic line narrowing was obtained experimentally and explained theoretically. This surprising behavior comes form molecular localization by forward-propagating and backward-propagating beams, which form a periodic lattice of low potentials in the fiber.
Publications
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Optics Express 21, 2195 (2013). "High-harmonic and single attosecond pulse generation using plasmonic field enhancement in ordered arrays of gold nanoparticles with chirped laser pulses"
Y.-Y. Yang, A. Scrinzi, A. Husakou, Q.-G. Li, S. L Stebbings, F. Süßmann, H.-J. Yu, S. Kim, E. Rühl, J. Herrmann, X.-C. Lin, and M. F. Kling
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Phys. Rev. A 90, 023831 (2014). "Quasi-phase-matched high-harmonic generation in composites of metal nanoparticles and a noble gas"
A. Husakou and J. Herrmann
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Nonlinear Phenomena in Complex Systems 18, 105 (2015). „Quasi-Phase-Matched High-Harmonic Generation by Modulation of Metal Nanoparticle Density in a Noble Gas“
A. Husakou, J. Herrmann, I. Kulagin, G. Boltaev, and T. Usmanov
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Nature Communications volume 7, Article number: 12779 (2016): „Raman gas self-organizing into deep nano-trap lattice“
M. Alharbi, A. Husakou, M. Chafer, B. Debord, F. Gerome, and F. Benabid
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Opt. Express 24, 3414 (2016). „Application of mid-infrared pulses for quasi-phase-matching of high-order harmonics in silver plasma“
R. A. Ganeev, A. Husakou, M. Suzuki, and H. Kuroda
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Quasi-phase-matched high harmonic generation in corrugated micrometer-scale waveguides
A. Husakou
