title: Off-axis metallic diffractive lens for terahertz beams.
abstract: A diffractive optical element for off-axis focusing of terahertz radiation is presented. It was designed in a nonparaxial regime and manufactured in a metal slab by laser cutting of curved stripes. The optical function of the structure includes focusing and deflecting the illuminating beam of a chosen frequency in a particular place. Therefore, the element acts as both a spatial and a spectral filter; hence it is especially suitable for separating the terahertz signal from a broadband thermal load in passive detection devices. The experimental evaluation of the proposed diffractive lens by means of time-domain spectroscopy is presented and discussed.
authors.affiliation: Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00 662 Warsaw, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Siemion
authors.forename: Andrzej
authors.initials: A
authors.lastname: Siemion
authors.forename: Michał
authors.initials: M
authors.lastname: Makowski
authors.forename: Maciej
authors.initials: M
authors.lastname: Sypek
authors.forename: Emilie
authors.initials: E
authors.lastname: Hérault
authors.forename: Frédéric
authors.initials: F
authors.lastname: Garet
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Coutaz