title: Engineered far-fields of metal-metal terahertz quantum cascade lasers with integrated planar horn structures.
abstract: The far-field emission profile of terahertz quantum cascade lasers (QCLs) in metal-metal waveguides is controlled in directionality and form through planar horn-type shape structures, whilst conserving a broad spectral response. The structures produce a gradual change in the high modal confinement of the waveguides and permit an improved far-field emission profile and resulting in a four-fold increase in the emitted output power. The two-dimensional far-field patterns are measured at 77 K and are agreement in with 3D modal simulations. The influence of parasitic high-order transverse modes is shown to be controlled by engineering the horn structure (ridge and horn widths), allowing only the fundamental mode to be coupled out.
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: I
authors.initials: I
authors.lastname: Kundu
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: E H
authors.initials: EH
authors.lastname: Linfield
authors.forename: A G
authors.initials: AG
authors.lastname: Davies
authors.forename: S
authors.initials: S
authors.lastname: Moumdji
authors.forename: R
authors.initials: R
authors.lastname: Colombelli
authors.forename: J
authors.initials: J
authors.lastname: Mangeney
authors.forename: J
authors.initials: J
authors.lastname: Tignon
authors.forename: S S
authors.initials: SS
authors.lastname: Dhillon