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Proceedings Paper

Laser processing for precise fabrication of the THz optics
Author(s): Bogdan Voisiat; Simonas Indrišiūnas; Ramūnas Šniaukas; Linas Minkevičius; Irmantas Kašalynas; Gediminas Račiukaitis
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Paper Abstract

Zone plates with integrated band-pass filters and binary Fresnel lenses designed for the THz spectral range were fabricated by direct laser ablation in metal films and the silicon substrate. Results on the process performance and quality of the products are reviewed. The focusing performance was measured using the THz source that produces the 580 GHz radiation. The beam was directed to the centre of the fabricated optical elements. Zone plates with integrated band-pass filters have shown the double performance in focusing and spectral selection. The dependence of ablation rate and surface roughness on the laser process parameters was thoroughly investigated on the silicon. The depth of the ablated grooves linearly depends on the number of laser scans number with a particular slope for each scanning speed. The process regime with the 125 mm/s scanning speed provided the most precise control over the ablation depth. The topography measurements of the laser fabricated multilevel phase zone plates (Fresnel lenses) with the 10 mm focal length showed good agreement with the calculated topography. The intensity distribution of the focus spots using the laser fabricated 2, 4 and 8 level binary Fresnel lenses showed better focusing performance when more depth levels were applied in the lens production.

Paper Details

Date Published: 20 February 2017
PDF: 10 pages
Proc. SPIE 10091, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII, 100910F (20 February 2017); doi: 10.1117/12.2253634
Show Author Affiliations
Bogdan Voisiat, Ctr. for Physical Sciences and Technology (Lithuania)
Simonas Indrišiūnas, Ctr. for Physical Sciences and Technology (Lithuania)
Ramūnas Šniaukas, Ctr. for Physical Sciences and Technology (Lithuania)
Linas Minkevičius, Ctr. for Physical Sciences and Technology (Lithuania)
Irmantas Kašalynas, Ctr. for Physical Sciences and Technology (Lithuania)
Gediminas Račiukaitis, Ctr. for Physical Sciences and Technology (Lithuania)


Published in SPIE Proceedings Vol. 10091:
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII
Beat Neuenschwander; Costas P. Grigoropoulos; Tetsuya Makimura; Gediminas Račiukaitis, Editor(s)

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