title: High-Q resonant cavities for terahertz quantum cascade lasers.
abstract: We report on the realization and characterization of two different designs for resonant THz cavities, based on wire-grid polarizers as input/output couplers, and injected by a continuous-wave quantum cascade laser (QCL) emitting at 2.55 THz. A comparison between the measured resonators parameters and the expected theoretical values is reported. With achieved quality factor Q ≈ 2.5 × 10(5), these cavities show resonant peaks as narrow as few MHz, comparable with the typical Doppler linewidth of THz molecular transitions and slightly broader than the free-running QCL emission spectrum. The effects of the optical feedback from one cavity to the QCL are examined by using the other cavity as a frequency reference.
authors.forename: A
authors.initials: A
authors.lastname: Campa
authors.forename: L
authors.initials: L
authors.lastname: Consolino
authors.forename: M
authors.initials: M
authors.lastname: Ravaro
authors.forename: D
authors.initials: D
authors.lastname: Mazzotti
authors.forename: M S
authors.initials: MS
authors.lastname: Vitiello
authors.forename: S
authors.initials: S
authors.lastname: Bartalini
authors.forename: P
authors.initials: P
authors.lastname: De Natale