title: Laser Feedback Interferometry as a Tool for Analysis of Granular Materials at Terahertz Frequencies: Towards Imaging and Identification of Plastic Explosives.
abstract: We propose a self-consistent method for the analysis of granular materials at terahertz (THz) frequencies using a quantum cascade laser. The method is designed for signals acquired from a laser feedback interferometer, and applied to non-contact reflection-mode sensing. Our technique is demonstrated using three plastic explosives, achieving good agreement with reference measurements obtained by THz time-domain spectroscopy in transmission geometry. The technique described in this study is readily scalable: replacing a single laser with a small laser array, with individual lasers operating at different frequencies will enable unambiguous identification of select materials. This paves the way towards non-contact, reflection-mode analysis and identification of granular materials at THz frequencies using quantum cascade lasers.
authors.affiliation: School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane QLD 4072, Australia. s.han@uq.edu.au.
authors.forename: She
authors.initials: S
authors.lastname: Han
authors.affiliation: School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane QLD 4072, Australia. bertling@itee.uq.edu.au.
authors.forename: Karl
authors.initials: K
authors.lastname: Bertling
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. P.Dean@leeds.ac.uk.
authors.forename: Paul
authors.initials: P
authors.lastname: Dean
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. el08jk@leeds.ac.uk.
authors.forename: James
authors.initials: J
authors.lastname: Keeley
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. A.D.Burnett@leeds.ac.uk.|School of Chemistry, University of Leeds, Leeds LS2 9JT, UK. A.D.Burnett@leeds.ac.uk.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Burnett
authors.affiliation: School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane QLD 4072, Australia. ylim@itee.uq.edu.au.
authors.forename: Yah Leng
authors.initials: YL
authors.lastname: Lim
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. khannasp@nplindia.org.
authors.forename: Suraj P
authors.initials: SP
authors.lastname: Khanna
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. A.Valavanis@leeds.ac.uk.
authors.forename: Alexander
authors.initials: A
authors.lastname: Valavanis
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. E.H.Linfield@leeds.ac.uk.
authors.forename: Edmund H
authors.initials: EH
authors.lastname: Linfield
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. g.davies@leeds.ac.uk.
authors.forename: A Giles
authors.initials: AG
authors.lastname: Davies
authors.affiliation: School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK. D.Indjin@leeds.ac.uk.
authors.forename: Dragan
authors.initials: D
authors.lastname: Indjin
authors.affiliation: School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia. t.taimre@uq.edu.au.
authors.forename: Thomas
authors.initials: T
authors.lastname: Taimre
authors.affiliation: School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane QLD 4072, Australia. rakic@itee.uq.edu.au.
authors.forename: Aleksandar D
authors.initials: AD
authors.lastname: Rakić
keywords: interferometry; optical constants; semiconductor lasers, quantum cascade; terahertz imaging