title: Terahertz beam steering and variable focusing using programmable diffraction gratings.
abstract: We propose a freely programmable THz diffraction grating based on an electrostatically actuated, computer controlled array of metallic cantilevers. Switching between different grating patterns enables tailoring spatio-temporal profiles of the THz waves. By characterizing the device with spatially resolved THz time domain spectroscopy, we demonstrate beam steering for a wide frequency band extending from 0.15 THz to 0.9 THz. The steerable range at 0.3 THz exceeds 40°. Focusing is also demonstrated by programming a chirped grating. The proposed approach could be employed to mimic arbitrary diffraction optics, enabling highly integrated and extremely flexible systems indispensable for THz stand-off imaging and communications.
authors: Department of Information Physics and Computing, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, 113-8656 Tokyo, Japan. monnai@alab.t.u-tokyo.ac.jp
authors: Yasuaki
authors: Y
authors: Monnai
authors: Kristian
authors: K
authors: Altmann
authors: Christian
authors: C
authors: Jansen
authors: Hartmut
authors: H
authors: Hillmer
authors: Martin
authors: M
authors: Koch
authors: Hiroyuki
authors: H
authors: Shinoda
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D008029:Lighting / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D055053:Terahertz Radiation