title: Continuous-wave optical parametric terahertz source.
abstract: Here, we present a continuous-wave optical parametric terahertz light source that does not require cooling. It coherently emits a diffraction-limited terahertz beam that is tunable from 1.3 to 1.7 THz with power levels exceeding 1 microW. Simultaneous phase matching of two nonlinear processes within one periodically-poled lithium niobate crystal, situated in an optical resonator, is employed: The signal wave of a primary parametric process is enhanced in this resonator. Therefore, its power is sufficient for starting a second process, generating a backwards traveling terahertz wave. Such a scheme of cascaded processes increases the output power of a terahertz system by more than one order of magnitude compared with non-resonant difference frequency generation due to high intracavity powers. The existence of linearly polarized terahertz radiation at 1.35 THz is confirmed by analyzing the terahertz light with metal grid polarizers and a Fabry-Pérot interferometer.
authors.affiliation: Institute of Physics, University of Bonn, Wegelerstr. 8, D-53115 Bonn, Germany.
authors.forename: Rosita
authors.initials: R
authors.lastname: Sowade
authors.forename: Ingo
authors.initials: I
authors.lastname: Breunig
authors.forename: Iván
authors.initials: I
authors.lastname: Cámara Mayorga
authors.forename: Jens
authors.initials: J
authors.lastname: Kiessling
authors.forename: Cristian
authors.initials: C
authors.lastname: Tulea
authors.forename: Volkmar
authors.initials: V
authors.lastname: Dierolf
authors.forename: Karsten
authors.initials: K
authors.lastname: Buse
mesh_terms: D000669:Amplifiers, Electronic; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting / Q000295:instrumentation*; D055053:Terahertz Radiation; D014159:Transducers