title: THz waveguide adapters for efficient radiation out-coupling from double metal THz QCLs.
abstract: We report the development of on-chip optical components designed to improve the out-coupling of double-metal terahertz (THz) frequency quantum cascade lasers (QCLs). A visible reshaping of the optical beam is achieved, independent of the precise waveguide configuration, by direct incorporation of cyclic-olefin copolymer (COC) dielectric optical fibers onto the QCL facet. A major improvement is further achieved by incorporating a micromachined feed-horn waveguide, assembled around the THz QCL and integrated with a slit-coupler. In its first implementation, we obtain a ± 20° beam divergence, offering the potential for high-efficiency radiation coupling from a metal-metal waveguide into optical fibers.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Castellano
authors.forename: Lianhe
authors.initials: L
authors.lastname: Li
authors.forename: Edmund H
authors.initials: EH
authors.lastname: Linfield
authors.forename: A Giles
authors.initials: AG
authors.lastname: Davies
authors.forename: Harvey E
authors.initials: HE
authors.lastname: Beere
authors.forename: David A
authors.initials: DA
authors.lastname: Ritchie
authors.forename: Miriam S
authors.initials: MS
authors.lastname: Vitiello