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Contribution Oral

THz radiation aplication

Reflective free-form optical elements for focusing of high-power THz radiation

Speakers

  • Prof. Vladimir PAVELYEV

Primary authors

Co-authors

Content

Appearance of the sources of coherent and high power THz radiation [1] opened new horizons for investigations in this frequency range [2]. High attention is focused on silicon diffractive optical elements (DOE), which are used for the beam manipulation [3-6]. The lithographic etching of a silicon substrate has been used in [3, 4] to fabricate binary relief of diffractive optical elements. Lithographic etching has disadvantages in the case of multilevel elements, because an expensive and complicated procedure of alignment of photomask is required. Binary (two-level) elements, in turn, have limited energy efficiency. The laser ablation technology has been used in [5, 6] for the fabrication of multilevel diffractive lens with high energy efficiency. However, diffractive optical elements are designed for working with monochromatic radiation of a fixed wavelength [7] only. The present talk is devoted to the fabrication of terahertz reflective free-form elements for transformation of high-power beams. Aluminium elements (spherical and cylindrical mirrors, reflective axicons) were fabricated by technology of micromilling. These optical elements were tested in the beam of the Novosibirsk Free Electron Laser at the wavelength of 129.5 μm. The measured diffractive efficiency of the spherical mirror (>94%) is in good agreement with both numerical calculations and theoretical predictions. Specific features and perspectives of the fabrication of optical elements by micromilling are discussed.

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