Contribution Invited Oral
Terahertz optical components for control of high-power FEL beams
- Prof. Vladimir PAVELYEV
The commissioning of coherent high-power sources of THz radiation  generated a need for optical elements to control this radiation. Optical elements for terahertz waves are somewhat different from the classical optical elements. In the case of high-power radiation, which damages conventional plastic lenses like polypropylene or TPX ones, the use of silicon diffractive optical elements (DOEs) solves the problem [2-6]. Binary silicon diffractive optical elements (diffractive lenses and beam splitters) for manipulation of the terahertz Novosibirsk Free Electron Laser (NovoFEL) radiation have been considered before in . Applications like imaging, material ablation, generation of continuous optical discharge, and even more exotic uses of the terahertz range, e.g. the field ionization of individual atoms, require focusing of THz radiation [3,4], often with an enhanced focal depth . Non-diffractive Bessel beams with angular orbital momentum (vortex beams) with different topological charges were formed using silicon binary phase axicons with spiral zone structures . Such beams have great potential for use in data transmission and remote sensing. Lithographic etching of silicon substrates [2 - 5], which is practiced in fabrication of binary elements, has disadvantages in the case of multilevel elements, when an expensive and complicated procedure of alignment of photomask is required. Binary (two-level) elements, in turn, have limited energy efficiency. A general possibility of laser-ablation microfabrication of silicon high-efficiency high-power diffractive optics for the terahertz range was shown in . The present work studies high-power optics for the terahertz range. Transmission and reflective optical elements for the terahertz range are considered, as well as antireflection structuring and antireflective coatings of silicon surface . The computational and experimental results are presented. REFERENCES
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