We study a new method in fabrication of THz optical components from previously studied porous three-dimensional nanostructures based on SiO2 [Optical Materials Express 10, 2100-2113 (2020)]. Porous SiO2 is represented by artificial opals [Optical Materials 49, 208–212 (2015)]. By the thermal treatment, it is able to achieve materials with different stoichiometric composition and porosity, and obtaining pre-determined physical and optical properties of thematerial. In this paper we produced the THz conical lens (axicone) by direct sedimentation of aqueous colloidal suspension of the SiO2 nanoparticles onto a shaped mold, followed by annealing and finished machining. The THz field transformation behind the axicone was studied by THz imaging system. The observed results were then compared with numerical predictions obtained by using the methods of computational electrodynamics. Finally, we discuss the potential of the described fabrication method in the THz optics.
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