title: Ultra-broadband room-temperature terahertz quantum cascade laser sources based on difference frequency generation.
abstract: We present ultra-broadband room temperature monolithic terahertz quantum cascade laser (QCL) sources based on intra-cavity difference frequency generation, emitting continuously more than one octave in frequency between 1.6 and 3.8 THz, with a peak output power of ~200 μW. Broadband terahertz emission is realized by nonlinear mixing between single-mode and multi-mode spectra due to distributed feedback grating and Fabry-Perot cavity, respectively, in a mid-infrared QCL with dual-upper-state active region design. Besides, at low temperature of 150 K, the device produces a peak power of ~1.0 mW with a broadband THz emission centered at 2.5 THz, ranging from 1.5 to 3.7 THz.
authors.forename: Kazuue
authors.initials: K
authors.lastname: Fujita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hitaka
authors.forename: Akio
authors.initials: A
authors.lastname: Ito
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yamanishi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Dougakiuchi
authors.forename: Tadataka
authors.initials: T
authors.lastname: Edamura