Abstract

We report on real-time gas sensing with a terahertz quantum-cascade laser (QCL). The method is solely based on the modulation of the external cavity length, exploiting the intermediate optical feedback regime. While the QCL is operated in continuous-wave mode, optical feedback results in a change of the QCL frequency as well as its terminal voltage. The first effect is exploited to tune the lasing frequency across a molecular absorption line. The second effect is used for the detection of the self-mixing signal. This allows for fast measurement times on the order of 10 ms per spectrum and for real-time measurements of gas concentrations with a rate of 100 Hz. This technique is demonstrated with a mixture of D2O and CH3OD in an absorption cell.

© 2017 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Evidence for frequency comb emission from a Fabry-Pérot terahertz quantum-cascade laser

M. Wienold, B. Röben, L. Schrottke, and H. T. Grahn
Opt. Express 22(25) 30410-30424 (2014)

Doppler-free spectroscopy with a terahertz quantum-cascade laser

M. Wienold, T. Alam, L. Schrottke, H. T. Grahn, and H.-W. Hübers
Opt. Express 26(6) 6692-6699 (2018)

Gas filter correlation instrument for air monitoring at submillimeter wavelengths

G. Mouret, W. Chen, D. Boucher, R. Bocquet, P. Mounaix, and D. Lippens
Opt. Lett. 24(5) 351-353 (1999)

References

  • View by:
  • |
  • |
  • |

  1. M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
  2. P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).
  3. L. Ho, M. Pepper, and P. Taday, “Terahertz spectroscopy: Signatures and fingerprints,” Nat. Photonics 2, 541–543 (2008).
  4. P. C. Ashworth, E. Pickwell-MacPherson, E. Provenzano, S. E. Pinder, A. D. Purushotham, M. Pepper, and V. P. Wallace, “Terahertz pulsed spectroscopy of freshly excised human breast cancer,” Opt. Express 17(15), 12444–12454 (2009).
    [PubMed]
  5. A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).
  6. L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).
  7. J. B. Baxter and G. W. Guglietta, “Terahertz Spectroscopy,” Anal. Chem. 83(12), 4342–4368 (2011).
    [PubMed]
  8. H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).
  9. S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).
  10. Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).
  11. P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
    [PubMed]
  12. A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
    [PubMed]
  13. Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).
  14. M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).
  15. T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).
  16. D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).
  17. X. Qi, G. Agnew, I. Kundu, T. Taimre, Y. L. Lim, K. Bertling, P. Dean, A. Grier, A. Valavanis, E. H. Linfield, A. Giles Davies, D. Indjin, and A. D. Rakić, “Multi-spectral terahertz sensing: proposal for a coupled-cavity quantum cascade laser based optical feedback interferometer,” Opt. Express 25(9), 10153–10165 (2017).
    [PubMed]
  18. L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).
  19. H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
    [PubMed]
  20. H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).
  21. T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
    [PubMed]
  22. R. Lang and K. Kobayashi, “External Optical Feedback Effects on Semiconductor Injection Laser Properties,” IEEE J. Quantum Electron. 16, 347–355 (1980).
  23. G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).
  24. L. A. Curtiss and M. Blander, “Thermodynamic Properties of Gas-Phase Hydrogen-Bonded Complexes,” Chem. Rev. 88, 827–841 (1988).
  25. S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
    [PubMed]
  26. J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
    [PubMed]

2017 (1)

2016 (4)

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

2015 (2)

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

2014 (1)

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

2013 (2)

A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
[PubMed]

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

2011 (4)

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

J. B. Baxter and G. W. Guglietta, “Terahertz Spectroscopy,” Anal. Chem. 83(12), 4342–4368 (2011).
[PubMed]

P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).

2010 (1)

2009 (1)

2008 (2)

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

L. Ho, M. Pepper, and P. Taday, “Terahertz spectroscopy: Signatures and fingerprints,” Nat. Photonics 2, 541–543 (2008).

2007 (1)

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).

2006 (1)

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

2003 (1)

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

2002 (2)

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

1998 (1)

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

1988 (1)

L. A. Curtiss and M. Blander, “Thermodynamic Properties of Gas-Phase Hydrogen-Bonded Complexes,” Chem. Rev. 88, 827–841 (1988).

1980 (1)

R. Lang and K. Kobayashi, “External Optical Feedback Effects on Semiconductor Injection Laser Properties,” IEEE J. Quantum Electron. 16, 347–355 (1980).

Agnew, G.

Ågren, H.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Ashworth, P. C.

Augustsson, A.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Bacon, D. R.

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

Bartalini, S.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Bartolini, P.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Baxter, J. B.

J. B. Baxter and G. W. Guglietta, “Terahertz Spectroscopy,” Anal. Chem. 83(12), 4342–4368 (2011).
[PubMed]

Beere, H.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Beere, H. E.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Bertling, K.

Biermann, K.

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

Blander, M.

L. A. Curtiss and M. Blander, “Thermodynamic Properties of Gas-Phase Hydrogen-Bonded Complexes,” Chem. Rev. 88, 827–841 (1988).

Bosch, T.

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

Burnett, A. D.

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

Cancio, P.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Cohen, E. A.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Consolino, L.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Cooke, D. G.

P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).

Crain, J.

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Cunningham, J. E.

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

Curtiss, L. A.

L. A. Curtiss and M. Blander, “Thermodynamic Properties of Gas-Phase Hydrogen-Bonded Complexes,” Chem. Rev. 88, 827–841 (1988).

Davies, A. G.

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
[PubMed]

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

De Natale, P.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

De Pas, M.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Dean, P.

X. Qi, G. Agnew, I. Kundu, T. Taimre, Y. L. Lim, K. Bertling, P. Dean, A. Grier, A. Valavanis, E. H. Linfield, A. Giles Davies, D. Indjin, and A. D. Rakić, “Multi-spectral terahertz sensing: proposal for a coupled-cavity quantum cascade laser based optical feedback interferometer,” Opt. Express 25(9), 10153–10165 (2017).
[PubMed]

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
[PubMed]

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

Degl’Innocenti, R.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

Delitsky, M. L.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Dixit, S.

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Donati, S.

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

Fan, W.

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

Finney, J. L.

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Freeman, J. R.

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

Giehler, M.

Giles Davies, A.

Giuliani, G.

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

Grahn, H. T.

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

Greiner-Bär, M.

Grier, A.

Guglietta, G. W.

J. B. Baxter and G. W. Guglietta, “Terahertz Spectroscopy,” Anal. Chem. 83(12), 4342–4368 (2011).
[PubMed]

Guo, J.-H.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Güsten, R.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Hagelschuer, T.

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

Harrison, P.

Hartogh, P.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Hey, R.

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

Ho, L.

L. Ho, M. Pepper, and P. Taday, “Terahertz spectroscopy: Signatures and fingerprints,” Nat. Photonics 2, 541–543 (2008).

Honingh, N.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Hübers, H.-W.

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Ikonic, Z.

Indjin, D.

Jarchow, C.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Jepsen, P. U.

P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).

Jessop, D. S.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

Kashtanov, S.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Khanna, S. P.

Klein, B.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Kliese, R.

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

Klimont, A.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

Kobayashi, K.

R. Lang and K. Kobayashi, “External Optical Feedback Effects on Semiconductor Injection Laser Properties,” IEEE J. Quantum Electron. 16, 347–355 (1980).

Koch, M.

P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).

Kundu, I.

Lachab, M.

Lang, R.

R. Lang and K. Kobayashi, “External Optical Feedback Effects on Semiconductor Injection Laser Properties,” IEEE J. Quantum Electron. 16, 347–355 (1980).

Li, L.

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

Lim, Y. L.

Linfield, E. H.

X. Qi, G. Agnew, I. Kundu, T. Taimre, Y. L. Lim, K. Bertling, P. Dean, A. Grier, A. Valavanis, E. H. Linfield, A. Giles Davies, D. Indjin, and A. D. Rakić, “Multi-spectral terahertz sensing: proposal for a coupled-cavity quantum cascade laser based optical feedback interferometer,” Opt. Express 25(9), 10153–10165 (2017).
[PubMed]

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
[PubMed]

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

Lü, X.

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

Luo, Y.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Mahler, L.

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Mohandas, R. A.

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

Müller, H. S. P.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Nikolic, M.

P. Dean, Y. L. Lim, A. Valavanis, R. Kliese, M. Nikolić, S. P. Khanna, M. Lachab, D. Indjin, Z. Ikonić, P. Harrison, A. D. Rakić, E. H. Linfield, and A. G. Davies, “Terahertz imaging through self-mixing in a quantum cascade laser,” Opt. Lett. 36(13), 2587–2589 (2011).
[PubMed]

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

Nordgren, J.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Norgia, M.

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

Pavlov, S. G.

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Pearson, J. C.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Pepper, M.

Pickett, H. M.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Pickwell-MacPherson, E.

Pinder, S. E.

Poon, W. C. K.

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Poynter, R. L.

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Provenzano, E.

Purushotham, A. D.

Qi, X.

Rakic, A. D.

Ren, Y.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

Rezac, L.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Richter, H.

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Ritchie, D.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Ritchie, D. A.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Rothbart, N.

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

Rubensson, J.-E.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Schrottke, L.

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

Semenov, A. D.

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Sharma, R.

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

Shuh, D. K.

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Soper, A. K.

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Taday, P.

L. Ho, M. Pepper, and P. Taday, “Terahertz spectroscopy: Signatures and fingerprints,” Nat. Photonics 2, 541–543 (2008).

Tahraoui, A.

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

Taimre, T.

Taschin, A.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Tonouchi, M.

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).

Torre, R.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Tredicucci, A.

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Valavanis, A.

Vitiello, M. S.

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Wallace, V. P.

Wallis, R.

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

Wienold, M.

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

T. Hagelschuer, N. Rothbart, H. Richter, M. Wienold, L. Schrottke, H. T. Grahn, and H.-W. Hübers, “High-spectral-resolution terahertz imaging with a quantum-cascade laser,” Opt. Express 24(13), 13839–13849 (2016).
[PubMed]

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

H. Richter, M. Greiner-Bär, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H.-W. Hübers, “A compact, continuous-wave terahertz source based on a quantum-cascade laser and a miniature cryocooler,” Opt. Express 18(10), 10177–10187 (2010).
[PubMed]

Wiesemeyer, H.

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Wilson, S. J.

A. D. Rakić, T. Taimre, K. Bertling, Y. L. Lim, P. Dean, D. Indjin, Z. Ikonić, P. Harrison, A. Valavanis, S. P. Khanna, M. Lachab, S. J. Wilson, E. H. Linfield, and A. G. Davies, “Swept-frequency feedback interferometry using terahertz frequency QCLs: a method for imaging and materials analysis,” Opt. Express 21(19), 22194–22205 (2013).
[PubMed]

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

Anal. Chem. (1)

J. B. Baxter and G. W. Guglietta, “Terahertz Spectroscopy,” Anal. Chem. 83(12), 4342–4368 (2011).
[PubMed]

Appl. Phys. Lett. (6)

H.-W. Hübers, S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie, “High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser,” Appl. Phys. Lett. 89, 061115 (2006).

Y. L. Lim, P. Dean, M. Nikolić, R. Kliese, S. P. Khanna, M. Lachab, A. Valavanis, D. Indjin, Z. Ikonić, P. Harrison, E. H. Linfield, A. G. Davies, S. J. Wilson, and A. D. Rakić, “Demonstration of a self-mixing displacement sensor based on terahertz quantum cascade lasers,” Appl. Phys. Lett. 99, 081108 (2011).

Y. Ren, R. Wallis, D. S. Jessop, R. Degl’Innocenti, A. Klimont, H. E. Beere, and D. A. Ritchie, “Fast terahertz imaging using a quantum cascade amplifier,” Appl. Phys. Lett. 107, 011107 (2015).

M. Wienold, T. Hagelschuer, N. Rothbart, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Real-time terahertz imaging through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 011102 (2016).

T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn, and H.-W. Hübers, “Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser,” Appl. Phys. Lett. 109, 191101 (2016).

D. R. Bacon, J. R. Freeman, R. A. Mohandas, L. Li, E. H. Linfield, A. G. Davies, and P. Dean, “Gain recovery time in a terahertz quantum cascade laser,” Appl. Phys. Lett. 108, 081104 (2016).

Astron. Astrophys. (1)

L. Rezac, P. Hartogh, R. Güsten, H. Wiesemeyer, H.-W. Hübers, C. Jarchow, H. Richter, B. Klein, and N. Honingh, “First detection of the 63 µm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA,” Astron. Astrophys. 580, L10 (2015).

Chem. Rev. (1)

L. A. Curtiss and M. Blander, “Thermodynamic Properties of Gas-Phase Hydrogen-Bonded Complexes,” Chem. Rev. 88, 827–841 (1988).

IEEE J. Quantum Electron. (1)

R. Lang and K. Kobayashi, “External Optical Feedback Effects on Semiconductor Injection Laser Properties,” IEEE J. Quantum Electron. 16, 347–355 (1980).

J. Opt. A, Pure Appl. Opt. (1)

G. Giuliani, M. Norgia, S. Donati, and T. Bosch, “Laser diode self-mixing technique for sensing applications,” J. Opt. A, Pure Appl. Opt. 4, S283–S294 (2002).

J. Quant. Spectrosc. Radiat. Transf. (1)

H. M. Pickett, R. L. Poynter, E. A. Cohen, M. L. Delitsky, J. C. Pearson, and H. S. P. Müller, “Submillimeter, millimeter, and microwave spectral line catalog,” J. Quant. Spectrosc. Radiat. Transf. 60, 883–890 (1998).

Laser Photonics Rev. (1)

P. U. Jepsen, D. G. Cooke, and M. Koch, “Terahertz spectroscopy and imaging – Modern techniques and applications,” Laser Photonics Rev. 5, 124–166 (2011).

Mater. Today (1)

A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today 11(8), 18–26 (2008).

Nat. Photonics (2)

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).

L. Ho, M. Pepper, and P. Taday, “Terahertz spectroscopy: Signatures and fingerprints,” Nat. Photonics 2, 541–543 (2008).

Nature (1)

S. Dixit, J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, “Molecular segregation observed in a concentrated alcohol-water solution,” Nature 416(6883), 829–832 (2002).
[PubMed]

Opt. Express (5)

Opt. Lett. (1)

Phys. Rev. Lett. (1)

J.-H. Guo, Y. Luo, A. Augustsson, S. Kashtanov, J.-E. Rubensson, D. K. Shuh, H. Ågren, and J. Nordgren, “Molecular Structure of Alcohol-Water Mixtures,” Phys. Rev. Lett. 91(15), 157401 (2003).
[PubMed]

Phys. Rev. X (1)

S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre, “Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy,” Phys. Rev. X 4, 021006 (2014).

Semicond. Sci. Technol. (1)

L. Schrottke, M. Wienold, R. Sharma, X. Lü, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H.-W. Hübers, and H. T. Grahn, “Quantum-cascade lasers as local oscillators for heterodyne spectrometers in the spectral range around 4.745 THz,” Semicond. Sci. Technol. 28, 035011 (2013).

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (6)

Fig. 1
Fig. 1 (a) Scheme of the experimental setup used for real-time gas sensing based on EOF. THz radiation is emitted by a QCL and focused onto a plane mirror mounted on a voice coil, which induces the self-mixing effect. The optical path consists of an absorption cell filled with D2O or CH3OD or a mixture of both species and a rotating wire grid. By changing the wire grid angle, the absorption signal can be directly measured with a Ge:Ga detector. (TMP: turbo molecular pump). (b) Transmission through the wire grid as a function of the wire grid angle δ for the EOF signal and the signal measured with the Ge:Ga detector. The transmission can be described with cosine functions with different phases as indicated by the red and blue lines. (c) Transmission spectrum of D2O (blue line) and CH3OD (red line) measured with the Ge:Ga detector at a pressure of 100 Pa. The frequency scale has been derived from the linear frequency-current characteristic and refers to the QCL operating point used for self-mixing.
Fig. 2
Fig. 2 (a) Calculated frequency shift Δν as a function of the normalized mirror displacement Δd/ΔdM for different feedback levels C0 as indicated for an evacuated absorption cell, i.e. Apk = 0. The solid lines refer to calculation results using Eq. (4), while the dashed lines refer to the exact solution of Eq. (1). The parameters are ds = 56 cm and ν0 = 4.745 THz. (b) Calculated values of Δν as a function of Δd/ΔdM evaluated using Eq. (6) for different absorption levels Apk of D2O as indicated at 300 K (Doppler broadened). The hysteresis at larger absorption levels is related to the forward and backward motion of the mirror.
Fig. 3
Fig. 3 (a) Calculated self-mixing voltage signal UEOF as a function of Δd/ΔdM for different absorption levels Apk at a moderate feedback level with C0 = 3.0 (αLEF = 0). The inset illustrates the line shape distortion in the apparent absorption due to nonlinearities in the frequency scale. (b) Hysteresis-induced separation dpk-pk of the peak positions as a function of Apk calculated at 300 K (Doppler broadened).
Fig. 4
Fig. 4 (a) Measured EOF signal as a function of the mirror oscillation phase for intermediate (red line, C0 = 3.1) and weak feedback (black line, C0 = 0.5). One oscillation period corresponds to an acquisition time of 20 ms with a sampling interval of 20 µs. At the intermediate feedback level, the D2O absorption appears as four sharp dips (indicated by blue arrows) due to forward and backward movement of the mirror. The green line is the result of a simulation of the EOF signal according to Eq. (7) with parameters C0 = 3.1, αLEF = 0.4, and m = −1 mV. (b) Simulation result of the EOF frequency shift as a function of the mirror oscillation phase. At the intermediate feedback level (red line, C0 = 3.1, αLEF = 0.4, m = −1 mV), the EOF induced frequency shift is sufficient to cover the D2O absorption frequency (indicated by the dashed blue line). At the weak feedback level (black line, C0 = 0.5, αLEF = 0.4, m = −1 mV), the frequency shift is not sufficient to sweep across the D2O absorption frequency.
Fig. 5
Fig. 5 (a) EOF signal as a function of of Δd/ΔdM during a sweep across the expected position dD2OdM of the D2O transition. For p = 2 Pa (blue line), the results of the forward and backward sweep are almost identical. For p = 20 Pa (red line), the absorption lines of the forward (FW) and backward (BW) sweep are shifted by a distance of dpk-pkdM due to hysteresis, and the observed peak absorption is reduced. (b) EOF transmission spectrum of the D2O absorption line for p = 2 Pa (blue line). The frequency scale corresponds to that of an empty cavity according to Eq. (4). The red line corresponds to a simulation result of the expected transmission spectrum.
Fig. 6
Fig. 6 (a) Peak absorption for D2O (blue points, A) and CH3OD (red points, B) as a function of time and pressure during CH3OD injection into the absorption cell, which is initially filled with D2O at 40 Pa. Each data point corresponds to an absorption spectrum, which has been measured within 10 ms. Three different regions I−III separated by dashed lines can be distinguished, for which the concentration of D2O is larger (I), similar (II), or less than that of CH3OD (III). The inset shows an exemplary spectrum measured in region II at the crossover of the CH3OD and D2O absorption. (b) The same measurement as in (a) obtained in a direct absorption configuration with a Ge:Ga detector.

Equations (9)

Equations on this page are rendered with MathJax. Learn more.

Δϕ= C 0 sin[Δϕ ϕ 0 +arctan( α LEF )].
arctan( α LEF ) ϕ s =2πN,
|Δd| < 1+ C 0 4π ν 0 c 1 Δ d M ,
Δν= ν 0 C 0 1+ C 0 Δd d .
C=T C 0 = e αL C 0 ,
Δϕ= C 1+C ( ϕ 0 ϕ s ).
U EOF =mCcos(ϕ)=mT C 0 cos[ arctan( α LEF )+ 1+ C 0 1+T C 0 Δd Δ d M ],
T= U EOF (gas) U EOF (ref) .
Δd= D m sin( ϕ m )+ d shift ,

Metrics