• Photonics Research
  • Vol. 11, Issue 11, 1814 (2023)
Robertas Grigutis, Vytautas Jukna, Gintaras Tamošauskas, and Audrius Dubietis*
Author Affiliations
  • Laser Research Center, Vilnius University, LT-10223 Vilnius, Lithuania
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    DOI: 10.1364/PRJ.494150 Cite this Article Set citation alerts
    Robertas Grigutis, Vytautas Jukna, Gintaras Tamošauskas, Audrius Dubietis, "Multiple conical odd harmonics from filament-inscribed nanogratings," Photonics Res. 11, 1814 (2023) Copy Citation Text show less

    Abstract

    We report on the observation of conical third, fifth, seventh, and ninth harmonics that gradually emerge during the supercontinuum generation by filamentation of femtosecond midinfrared pulses in lithium strontium hexafluoroaluminate crystal. We show that the generation of conical odd harmonics is an optical signature of light-driven material reorganization in the form of volume nanogratings at the site irradiated by repetitive femtosecond filaments. The angle-resolved spectral measurements demonstrate remarkably broad spectra of individual odd harmonics, benefiting from a spectrally broadened pump pulse (supercontinuum), and reveal that filament-inscribed nanogratings represent photonic structures that are able to provide ultrabroad phase-matching bandwidths covering the wavelength range from the ultraviolet to the near infrared. We propose a scenario that interprets the generation of conical fifth, seventh, and ninth harmonics as nanograting phase-matched cascaded noncollinear four-wave mixing processes.
    k3=3k1+G3,k5=k3+2k1+G5,k7=k5+2k1+G7,k9=k7+2k1+G9,

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    cosα3=n1n3,cosα5=n1n5,cosα7=n1n7,cosα9=n1n9,

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    Λ3=(n32n12λ3)1,Λ5=(n52n12λ51Λ3)1,Λ7=(n72n12λ71Λ31Λ5)1,Λ9=(n92n12λ91Λ31Λ51Λ7)1,

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    Robertas Grigutis, Vytautas Jukna, Gintaras Tamošauskas, Audrius Dubietis, "Multiple conical odd harmonics from filament-inscribed nanogratings," Photonics Res. 11, 1814 (2023)
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