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Contribution Invited Oral

Budker INP - Conference Hall
SR and FEL sources and centers

Fabrication of high effective power silicon diffractive optics of terahertz range by femtosecond laser ablation of silicon surface

Speakers

  • Prof. Vladimir PAVELYEV

Primary authors

Co-authors

Content

The emergence of coherent, high power sources of THz radiation [1] has formed a need for optical elements to control this radiation. It is known that high-power THz beams can be controlled by silicon diffractive optical elements (DOEs) [2,3,4]. The lithographic etching of a silicon substrate [2,3,4] has disadvantages: fabrication of multi-level elements by lithographic etching requires an expensive and complicated procedure of photomask alignment, and binary (two-level) elements have limited energy efficiency. A possibility of the microfabrication of a high-effective power silicon diffractive optics for terahertz range by laser ablation is investigated [5]. A four-level silicon diffractive THz Fresnel lens has been fabricated for the first time by femtosecond laser ablation [5]. High repetition (f = 200 kHz) femtosecond Yb:YAG laser was used for the formation of micro-relief at the silicon surface. Features of the lens were investigated in the beam of the free electron laser at the wavelength of 141 µm. The measured diffractive efficiency of the lens is in good agreement with the theoretical prediction [5]. The experiments have shown the feasibility of laser ablation of the silicon surface to fabricate effective multilevel THz DOEs. Improving the proposed technology of forming a silicon microrelief, in particular increasing the number of its quantization levels, will eventually increase the energy efficiency of silicon DOEs designed to control beams of THz radiation.

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  4. Knyazev B.A. Generation of Terahertz Surface Plasmon Polaritons Using Nondiffractive Bessel Beams with Orbital Angular Momentum// Yu.Yu. Choporova, M.S. Mitkov, V.S. Pavelyev, B.O. Volodkin/Phys. Rev. Lett.- 2015-Vol 115 -163901.
  5. Komlenok, M.S. Fabrication of a multilevel THz Fresnel lens by femtosecond laser ablation// B.O. Volodkin, B.A. Knyazev, V.V. Kononenko, T.V. Kononenko, V.I. Konov, V.S. Pavelyev, V.A. Soifer, K.N. Tukmakov, Yu.Yu. Choporova/Quantum Electronics-2015-Vol. 45, N 10- 933 –936.