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Title: 8-beam local oscillator array at 47 THz generated by a phase grating and a quantum cascade laser

We present an 8-beam local oscillator (LO) for the astronomically significant [OI] line at 4.7 THz. The beams are generated using a quantum cascade laser (QCL) in combination with a Fourier phase grating. The grating is fully characterized using a third order distributed feedback (DFB) QCL with a single mode emission at 4.7 THz as the input. The measured diffraction efficiency of 74.3% is in an excellent agreement with the calculated result of 75.4% using a 3D simulation. We show that the power distribution among the diffracted beams is uniform enough for pumping an array receiver. To validate the grating bandwidth, we apply a far-infrared (FIR) gas laser emission at 5.3 THz as the input and find a very similar performance in terms of efficiency, power distribution, and spatial configuration of the diffracted beams. Both results represent the highest operating frequencies of THz phase gratings reported in the literature. By injecting one of the eight diffracted 4.7 THz beams into a superconducting hot electron bolometer (HEB) mixer, we find that the coupled power, taking the optical loss into account, is in consistency with the QCL power value.
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6]
  1. Delft University of Technology (The Netherlands). Kavli Institute of Nanoscience
  2. SRON Netherlands Institute for Space Research (The Netherlands)
  3. Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Department of Electrical Engineering and Computer Science
  5. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies
  6. Delft University of Technology (The Netherlands). Kavli Institute of Nanoscience; SRON Netherlands Institute for Space Research (The Netherlands)
Publication Date:
Report Number(s):
Journal ID: ISSN 1094-4087; OPEXFF; 656371; TRN: US1800249
Grant/Contract Number:
AC04-94AL85000; NA0003525
Accepted Manuscript
Journal Name:
Optics Express
Additional Journal Information:
Journal Volume: 25; Journal Issue: 24; Journal ID: ISSN 1094-4087
Optical Society of America (OSA)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC)
Country of Publication:
United States
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 24 POWER TRANSMISSION AND DISTRIBUTION; Diffraction gratings; Semiconductor lasers; quantum cascade; Heterodyne; Far infrared or terahertz; Arrays; Astronomical optics
OSTI Identifier: