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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
Authors:
 [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):
SAND-2017-2577J
Journal ID: ISSN 2334-2536; 651590
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Optica
Additional Journal Information:
Journal Volume: 4; Journal Issue: 7; Journal ID: ISSN 2334-2536
Publisher:
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
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; semiconductor lasers, quantum cascade; semiconductor lasers; laser amplifiers; optical amplifiers; semiconductor optical amplifiers
OSTI Identifier:
1372355

Kao, Tsung -Yu, Reno, John L., and Hu, Qing. Amplifiers of free-space terahertz radiation. United States: N. p., Web. doi:10.1364/optica.4.000713.
Kao, Tsung -Yu, Reno, John L., & Hu, Qing. Amplifiers of free-space terahertz radiation. United States. doi:10.1364/optica.4.000713.
Kao, Tsung -Yu, Reno, John L., and Hu, Qing. 2017. "Amplifiers of free-space terahertz radiation". United States. doi:10.1364/optica.4.000713. https://www.osti.gov/servlets/purl/1372355.
@article{osti_1372355,
title = {Amplifiers of free-space terahertz radiation},
author = {Kao, Tsung -Yu and Reno, John L. and Hu, Qing},
abstractNote = {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 be categorized as active metasurface, with the ability to amplify or absorb specific frequency components of the input THz signal.},
doi = {10.1364/optica.4.000713},
journal = {Optica},
number = 7,
volume = 4,
place = {United States},
year = {2017},
month = {7}
}