title: Linewidth and tuning characteristics of terahertz quantum cascade lasers.
abstract: We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 kHz. Characteristics are also reported for frequency tuning as the injection current is varied.
authors.affiliation: Department of Electrical and Computer Engineering, MS-366, Rice University, Houston, Texas 77251-1892, USA.
authors.forename: A
authors.initials: A
authors.lastname: Barkan
authors.forename: F K
authors.initials: FK
authors.lastname: Tittel
authors.forename: D M
authors.initials: DM
authors.lastname: Mittleman
authors.forename: R
authors.initials: R
authors.lastname: Dengler
authors.forename: P H
authors.initials: PH
authors.lastname: Siegel
authors.forename: G
authors.initials: G
authors.lastname: Scalari
authors.forename: L
authors.initials: L
authors.lastname: Ajili
authors.forename: J
authors.initials: J
authors.lastname: Faist
authors.forename: H E
authors.initials: HE
authors.lastname: Beere
authors.forename: E H
authors.initials: EH
authors.lastname: Linfield
authors.forename: A G
authors.initials: AG
authors.lastname: Davies
authors.forename: D A
authors.initials: DA
authors.lastname: Ritchie