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Dual-frequency imaging using an electrically tunable terahertz quantum cascade laser
Paul Dean, Nor Kamila Saat, Suraj P. Khanna, Mohammed Salih, Andrew Burnett, John Cunningham, Edmund H. Linfield, and A. Giles Davies »View Author Affiliations
School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
*Corresponding author: p.dean@leeds.ac.uk
Optics Express, Vol. 17, Issue 23, pp. 20631-20641 (2009)
http://dx.doi.org/10.1364/OE.17.020631
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Abstract
We report dual-frequency transmission imaging of polycrystalline materials using an electrically tunable terahertz (THz) frequency quantum cascade laser (QCL). Using our system we are able to obtain images at both 3.05 THz and 3.24 THz in a single two-dimensional scan of a sample. By taking the difference of the natural logarithms of the transmission coefficients obtained at each frequency, the difference-attenuation coefficient is determined, and evaluated for samples of lactose monohydrate, glucose monohydrate, sucrose, and the high explosive PETN. We also demonstrate difference-intensity imaging at these frequencies by combining amplitude modulation of the QCL bias with lock-in detection. Owing to the specific molecular absorption spectra of these materials in the THz frequency range, the samples can be distinguished using our technique.
© 2009 OSA
OCIS Codes
(140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade
(110.6795) Imaging systems : Terahertz imaging
ToC Category:
Imaging Systems
History
Original Manuscript: August 27, 2009
Revised Manuscript: October 16, 2009
Manuscript Accepted: October 20, 2009
Published: October 26, 2009
Citation
Paul Dean, Nor Kamila Saat, Suraj P. Khanna, Mohammed Salih, Andrew Burnett, John Cunningham, Edmund H. Linfield, and A. Giles Davies, "Dual-frequency imaging using an electrically tunable terahertz quantum cascade laser," Opt. Express 17, 20631-20641 (2009)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-23-20631
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References
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- S. Mair, B. Gompf, and M. Dressel, “Microspectroscopy and imaging in the THz range using coherent CW radiation,” Phys. Med. Biol. 47(21), 3719–3725 (2002). [CrossRef] [PubMed]
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- T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffmann, M. Breede, M. Hofmann, G. Hein, K. Pierz, M. Sperling, and K. Donhuijsen, “Continuous-wave THz imaging,” Electron. Lett. 37(24), 1461–1462 (2001). [CrossRef]
- T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffmann, M. Breede, M. Hofmann, G. Hein, K. Pierz, M. Sperling, and K. Donhuijsen, “Continuous-wave THz imaging,” Electron. Lett. 37(24), 1461–1462 (2001). [CrossRef]
- T. Kleine-Ostmann, P. Knobloch, M. Koch, S. Hoffmann, M. Breede, M. Hofmann, G. Hein, K. Pierz, M. Sperling, and K. Donhuijsen, “Continuous-wave THz imaging,” Electron. Lett. 37(24), 1461–1462 (2001). [CrossRef]
- M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16(5), 3242–3248 (2008), http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-5-3242 . [CrossRef] [PubMed]
- C. Walther, M. Fischer, G. Scalari, R. Terazzi, N. Hoyler, and J. Faist, “Quantum cascade lasers operating from 1.2 to 1.6 THz,” Appl. Phys. Lett. 91(13), 131122 (2007). [CrossRef]
- S. M. Kim, F. Hatami, J. S. Harris, A. W. Kurian, J. Ford, D. King, G. Scalari, M. Giovannini, N. Hoyler, J. Faist, and G. Harris, “Biomedical terahertz imaging with a quantum cascade laser,” Appl. Phys. Lett. 88(15), 153903–153905 (2006). [CrossRef]
- S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum-cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94(13), 131105–131107 (2009). [CrossRef]
- B. Williams, S. Kumar, Q. Hu, and J. L. Reno, “High-power terahertz quantum-cascade lasers,” Electron. Lett. 42(2), 89–90 (2006). [CrossRef]
- A. W. M. Lee, Q. Qin, S. Kumar, B. S. Williams, Q. Hu, and J. L. Reno, “Real-time terahertz imaging over a standoff distance (>25 meters),” Appl. Phys. Lett. 89(14), 141125–141127 (2006). [CrossRef]
- N. Karpowicz, H. Zhong, C. Zhang, K. Lin, J. Hwang, J. Xu, and X.-C. Zhang, “Compact continuous-wave subterahertz system for inspection applications,” Appl. Phys. Lett. 86(5), 054105–054107 (2005). [CrossRef]
- N. Karpowicz, H. Zhong, J. Xu, K. Lin, J. S. Hwang, and X.-C. Zhang, “Comparison between pulsed terahertz time-domain imaging and continuous wave terahertz imaging,” Semicond. Sci. Technol. 20(7), S293–S299 (2005). [CrossRef]
- Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa, and H. Minamide, “Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,” Appl. Phys. Lett. 83(4), 800–802 (2003). [CrossRef]
- R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002). [CrossRef] [PubMed]
- Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa, and H. Minamide, “Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,” Appl. Phys. Lett. 83(4), 800–802 (2003). [CrossRef]
- Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa, and H. Minamide, “Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,” Appl. Phys. Lett. 83(4), 800–802 (2003). [CrossRef]
- N. Karpowicz, H. Zhong, J. Xu, K. Lin, J. S. Hwang, and X.-C. Zhang, “Comparison between pulsed terahertz time-domain imaging and continuous wave terahertz imaging,” Semicond. Sci. Technol. 20(7), S293–S299 (2005). [CrossRef]
- N. Karpowicz, H. Zhong, C. Zhang, K. Lin, J. Hwang, J. Xu, and X.-C. Zhang, “Compact continuous-wave subterahertz system for inspection applications,” Appl. Phys. Lett. 86(5), 054105–054107 (2005). [CrossRef]
- A. Dobroiu, M. Yamashita, Y. N. Ohshima, Y. Morita, C. Otani, and K. Kawase, “Terahertz imaging system based on a backward-wave oscillator,” Appl. Opt. 43(30), 5637–5646 (2004). [CrossRef] [PubMed]
- Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa, and H. Minamide, “Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,” Appl. Phys. Lett. 83(4), 800–802 (2003). [CrossRef]
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- Y. C. Shen, T. Lo, P. F. Taday, B. E. Cole, R. Tribe, and M. C. Kemp, “Detection and identification of explosives using terahertz pulsed spectroscopic imaging,” Appl. Phys. Lett. 86(24), 241116–241118 (2005). [CrossRef]
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