title: 2.32 THz quantum cascade laser frequency-locked to the harmonic of a microwave synthesizer source.
abstract: Frequency stabilization of a THz quantum cascade laser (QCL) to the harmonic of a microwave source has been accomplished using a Schottky diode waveguide mixer designed for harmonic mixing. The 2.32 THz, 1.0 milliwatt CW QCL is coupled into the signal port of the mixer and a 110 GHz signal, derived from a harmonic of a microwave synthesizer, is coupled into the IF port. The difference frequency between the 21st harmonic of 110 GHz and the QCL is used in a discriminator to adjust the QCL bias current to stabilize the frequency. The short-term frequency jitter is reduced from 550 kHz to 4.5 kHz (FWHM) and the long-term frequency drift is eliminated. This performance is compared to that of several other THz QCL frequency stabilization techniques.
authors.affiliation: Photonics Center, Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA. Andriy_Danylov@uml.edu
authors.forename: Andriy A
authors.initials: AA
authors.lastname: Danylov
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Light
authors.forename: Jerry
authors.initials: J
authors.lastname: Waldman
authors.forename: Neal R
authors.initials: NR
authors.lastname: Erickson
authors.forename: Xifeng
authors.initials: X
authors.lastname: Qian
authors.forename: William D
authors.initials: WD
authors.lastname: Goodhue
mesh_terms: D004581:Electronics / Q000295:instrumentation; D004867:Equipment Design; D054023:Lasers, Semiconductor; D008872:Microwaves; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D055053:Terahertz Radiation