title: Coupling terahertz radiation between sub-wavelength metal-metal waveguides and free space using monolithically integrated horn antennae.
abstract: Broadband horn antennae are presented that efficiently couple terahertz radiation between sub-wavelength metal-metal waveguides and free space. Sub-picosecond terahertz pulses were coupled into and out from sub-wavelength parallel-plate waveguides by using the horn antennae in a terahertz time-domain spectrometer. Monolithic antennae were fabricated at the facets of metal-metal terahertz quantum cascade lasers, and laser action was observed for devices emitting at 1.4 THz, 2.3 THz and 3.2 THz. A good far-field laser radiation pattern (FWHM less than 11 degrees) is obtained as a result of the significant expansion of the optical mode by the antenna.
authors.affiliation: Institute for Quantum Electronics, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Lloyd-Hughes
authors.forename: G
authors.initials: G
authors.lastname: Scalari
authors.forename: A
authors.initials: A
authors.lastname: van Kolck
authors.forename: M
authors.initials: M
authors.lastname: Fischer
authors.forename: M
authors.initials: M
authors.lastname: Beck
authors.forename: J
authors.initials: J
authors.lastname: Faist
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008670:Metals / Q000737:chemistry*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D055053:Terahertz Radiation; D055068:Terahertz Spectroscopy / Q000295:instrumentation* / Q000379:methods*
chemical_list: D008670:Metals