title: Efficient coupling of double-metal terahertz quantum cascade lasers to flexible dielectric-lined hollow metallic waveguides.
abstract: The growth in terahertz frequency applications utilising the quantum cascade laser is hampered by a lack of targeted power delivery solutions over large distances (>100 mm). Here we demonstrate the efficient coupling of double-metal quantum cascade lasers into flexible polystyrene lined hollow metallic waveguides via the use of a hollow copper waveguide integrated into the laser mounting block. Our approach exhibits low divergence, Gaussian-like emission, which is robust to misalignment error, at distances > 550 mm, with a coupling efficiency from the hollow copper waveguide into the flexible waveguide > 90%. We also demonstrate the ability to nitrogen purge the flexible waveguide, increasing the power transmission by up to 20% at 2.85 THz, which paves the way for future fibre based terahertz sensing and spectroscopy applications.
authors.forename: R
authors.initials: R
authors.lastname: Wallis
authors.forename: R
authors.initials: R
authors.lastname: Degl'Iinnocenti
authors.forename: D S
authors.initials: DS
authors.lastname: Jessop
authors.forename: Y
authors.initials: Y
authors.lastname: Ren
authors.forename: A
authors.initials: A
authors.lastname: Klimont
authors.forename: Y D
authors.initials: YD
authors.lastname: Shah
authors.forename: O
authors.initials: O
authors.lastname: Mitrofanov
authors.forename: C M
authors.initials: CM
authors.lastname: Bledt
authors.forename: J E
authors.initials: JE
authors.lastname: Melzer
authors.forename: J A
authors.initials: JA
authors.lastname: Harrington
authors.forename: H E
authors.initials: HE
authors.lastname: Beere
authors.forename: D A
authors.initials: DA
authors.lastname: Ritchie