title: Long-range guided THz radiation by thin layers of water.
abstract: We propose a novel method to guide THz radiation with low losses along thin layers of water. This approach is based on the coupling of evanescent surface fields at the opposite sides of the thin water layer surrounded by a dielectric material, which leads to a maximum field amplitude at the interfaces and a reduction of the energy density inside the water film. In spite of the strong absorption of water in this frequency range, calculations show that the field distribution can lead to propagation lengths of several centimeters. By means of attenuated total reflection measurements we demonstrate the coupling of incident THz radiation to the long-range surface guided modes across a layer of water with a thickness of 24 μm. This first demonstration paves the way for THz sensing in aqueous environments.
authors.affiliation: Institute of High Frequency and Quantum Electronics (HQE), University of Siegen, Siegen, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Sczech
authors.forename: Jaime Gómez
authors.initials: JG
authors.lastname: Rivas
authors.forename: Audrey
authors.initials: A
authors.lastname: Berrier
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Giannini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pirruccio
authors.forename: Christian
authors.initials: C
authors.lastname: Debus
authors.forename: Heiko
authors.initials: H
authors.lastname: Schäfer-Eberwein
authors.forename: Peter Haring
authors.initials: PH
authors.lastname: Bolívar
mesh_terms: D004463:Ecology / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D008962:Models, Theoretical; D012031:Refractometry / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties / Q000528:radiation effects*; D055053:Terahertz Radiation; D055068:Terahertz Spectroscopy / Q000295:instrumentation / Q000379:methods*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water