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Title: Terahertz multiheterodyne spectroscopy using laser frequency combs

The terahertz region is of great importance for spectroscopy since many molecules have absorption fingerprints there. Frequency combs based on terahertz quantum cascade lasers feature broadband coverage and high output powers in a compact package, making them an attractive option for broadband spectroscopy. Here, we demonstrate the first multiheterodyne spectroscopy using two terahertz quantum cascade laser combs. Over a spectral range of 250 GHz, we achieve average signal-to-noise ratios of 34 dB using cryogenic detectors and 24 dB using room-temperature detectors, all in just 100 μs. As a proof of principle, we use these combs to measure the broadband transmission spectrum of etalon samples and show that, with proper signal processing, it is possible to extend the multiheterodyne spectroscopy to quantum cascade laser combs operating in pulsed mode. Here, this greatly expands the range of quantum cascade lasers that could be suitable for these techniques and allows for the creation of completely solid-state terahertz laser spectrometers.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. SRON Netherlands Institute for Space Research, Groningen (The Netherlands)
  3. SRON Netherlands Institute for Space Research, Groningen (The Netherlands); Delft Univ. of Technology, Delft (The Netherlands)
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
OSTI Identifier:
1251435
Report Number(s):
SAND-2016-1933J
Journal ID: ISSN 2334-2536; 619787
Grant/Contract Number:
AC04-94AL85000
Type:
Published Article
Journal Name:
Optica
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; 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:
47 OTHER INSTRUMENTATION; lasers; semiconductor lasers; quantum cascade; spectroscopy; terahertz; spectroscopy heterodyne; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 42 ENGINEERING; heterodyne