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Title: Amplifiers of free-space terahertz radiation

Here, amplifiers of free-space radiation are quite useful, especially in spectral ranges where the radiation is weak and sensitive detectors are hard to come by. A preamplification of the said weak radiation signal will significantly boost the S/N ratio in remote sensing and imaging applications. This is especially true in the terahertz (THz) range where the radiation signal is often weak and sensitive detectors require the cooling of liquid helium. Although quantum cascade structures are promising for providing amplification in the terahertz band from 2 to 5 THz, a THz amplifier has been demonstrated in an integrated form, in which the source is in close proximity to the amplifier, which will not be suitable for the aforementioned applications. Here we demonstrate what we believe is a novel approach to achieve significant amplification of free-space THz radiation using an array of short-cavity, surface-emitting THz quantum cascade lasers operating marginally below the lasing threshold as a Fabry–Perot amplifier. This free-space “slow light” amplifier provides 7.5 dB(×5.6) overall gain at ~3.1 THz. The proposed devices are suitable for low-noise pre-amplifiers in heterodyne detection systems and for THz imaging systems. With the sub-wavelength pixel size of the array, the reflective amplifier can also bemore » categorized as active metasurface, with the ability to amplify or absorb specific frequency components of the input THz signal.« less
 [1] ;  [2] ;  [3]
  1. LongWave Photonics LLC, Mountain View, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2334-2536; 651590
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 4; Journal Issue: 7; Journal ID: ISSN 2334-2536
Optical Society of America
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; semiconductor lasers, quantum cascade; semiconductor lasers; laser amplifiers; optical amplifiers; semiconductor optical amplifiers
OSTI Identifier: