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Valavanis, A; Chowdhury, S; Burnett, AD; Clarkson, AR; Bacon, DR; Khanna, SP; Davies, AG; Linfield, EH; Dean, P (2016)
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Languages: English
Types: Article
We demonstrate diffuse-reflectance (DR) spectroscopy of powders using a discretely-tunable terahertz-frequency quantum cascade laser (THz QCL) with a heterogeneous active region. DR signatures were obtained at frequencies of 3.06, 3.21, 3.28 and 3.35 THz, and the relative absorption coefficients were inferred at each frequency using a Kubelka–Munk (KM) scattering model. The spectral lineshapes reproduce the absolute Beer–Lambert (BL) absorption spectra of a range of materials, which were also measured using conventional transmission-mode THz time-domain spectroscopy. It is shown that the DR technique works reliably for materials that include pharmaceutical compounds and foodstuffs, with BL absorption coefficients in the range 2–10 mm−1. This method is potentially suitable for automated material identification, without any requirement for a priori knowledge of the refractive index or scattering properties of the sampled material.
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    • [1] J. A. Zeitler, P. F. Taday, D. A. Newnham, M. Pepper, K. C. Gordon, and T. Rades, “Terahertz pulsed spectroscopy and imaging in the pharmaceutical setting -A review,” J. Pharm. Pharmacol., vol. 59, no. 2, pp. 209-223, 2007.
    • [2] A. J. Fitzgerald, E. Berry, N. N. Zinovev, G. C. Walker, M. A. Smith, and J. M. Chamberlain, “An introduction to medical imaging with coherent terahertz frequency radiation,” Phys. Med. Biol., vol. 47, no. 7, Apr. 2002, Art no R67.
    • [3] K. Kawase, Y. Ogawa, Y. Watanabe, and H. Inoue, “Non-destructive terahertz imaging of illicit drugs using spectral fingerprints,” Opt. Express, vol. 11, no. 20, pp. 2549-2554, Oct. 2003.
    • [4] A. G. Davies, A. D. Burnett, W. Fan, E. H. Linfield, and J. E. Cunningham, “Terahertz spectroscopy of explosives and drugs,” Mater. Today, vol. 11, no. 3, pp. 18-26, 2008.
    • [5] H.-B. Liu, Y. Chen, G. J. Bastiaans, and X.-C. Zhang, “Detection and identification of explosive RDX by THz diffuse reflection spectroscopy,” Opt. Express, vol. 14, no. 1, pp. 415-423, Jan. 2006.
    • [6] D. J. J. Fraser and P. R. Griffiths, “Effect of scattering coefficient on diffuse reflectance infrared spectra,” Appl. Spectrosc., vol. 44, no. 2, pp. 193-199, Feb. 1990.
    • [7] P. Dean et al., “Absorption-sensitive diffuse reflection imaging of concealed powders using a terahertz quantum cascade laser,” Opt. Express, vol. 16, no. 9, pp. 5997-6007, Apr. 2008.
    • [8] P. Dean et al., “Measurement and analysis of the diffuse reflectance of powdered samples at terahertz frequencies using a quantum cascade laser,” J. Chem. Phys., vol. 134, no. 13, p. 134304, Apr. 2011.
    • [9] S. P. Khanna, M. Salih, P. Dean, A. G. Davies, and E. H. Linfield, “Electrically tunable terahertz quantum-cascade laser with a heterogeneous active region,” Appl. Phys. Lett., vol. 95, no. 18, p. 181101, Nov. 2009.
    • [10] H. Luo, S. R. Laframboise, Z. R. Wasilewski, G. C. Aers, H. C. Liu, and J. C. Cao, “Terahertz quantum-cascade lasers based on a three-well active module,” Appl. Phys. Lett., vol. 90, no. 4, Jan. 2007, Art no 041112.
    • [11] S. P. Khanna, S. Chakraborty, M. Lachab, N. M. Hinchcliffe, E. H. Linfield, and A. G. Davies, “The growth and measurement of terahertz quantum cascade lasers,” Physica E, vol. 40, no. 6, pp. 1859-1861, Apr. 2008.
    • [12] J. W. Coltman, “The specification of imaging properties by response to a sine wave input,” J. Opt. Soc. Amer., vol. 44, no. 6, p. 468, 1954.
    • [13] H. Rinne, The Weibull Distribution: A Handbook. Boca Raton, FL, USA: CRC Press, 2008.
    • [14] L. Tsang and J. A. Kong, “Multiple scattering of electromagnetic waves by random distributions of discrete scatterers with coherent potential and quantum mechanical formalism,” J. Appl. Phys., vol. 51, no. 7, pp. 3465-3485, Jul. 1980.
    • [15] J. D. Lindberg, “Absolute diffuse reflectance from relative reflectance measurements,” Appl. Opt., vol. 26, no. 14, pp. 2900-2905, Jul. 1987.
    • [16] J. D. Lindberg, R. E. Douglass, and D. M. Garvey, “Absorption-coefficient-determination method for particulate materials,” Appl. Opt., vol. 33, no. 19, pp. 4314-4319, Jul. 1994.
    • [17] A. D. Burnett et al., “Calculation and measurement of terahertz active normal modes in crystalline PETN,” Chem. Phys. Chem., vol. 11, no. 2, pp. 368-378, 2010.
    • [18] P. U. Jepsen and B. Fischer, “Dynamic range in terahertz time-domain transmission and reflection spectroscopy,” Opt. Lett., vol. 30, no. 1, pp. 29-31, Jan. 2005.
    • [19] A. D. Burnett et al., “Broadband terahertz time-domain spectroscopy of drugs-of-abuse and the use of principal component analysis,” Analyst, vol. 134, no. 8, pp. 1658-1668, Jul. 2009.
    • [20] I. Kundu et al., “Discrete Vernier tuning in terahertz quantum cascade lasers using coupled cavities,” Opt. Express, vol. 22, no. 13, pp. 16595-16605, Jun. 2014.
    • [21] M. Vitiello and A. Tredicucci, “Tunable emission in THz quantum cascade lasers,” IEEE Trans. THz Sci. Technol., vol. 1, no. 1, pp. 76-84, Sep. 2011.
    • Paul Dean received the M.Phys. (Hons.) degree in physics in 2001 and the Ph.D. degree in laser physics in 2005, both from the University of Manchester, Manchester, U.K. In 2005, he was appointed as a Post-Doctoral Research Associate at the Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds, Leeds, U.K., and as a University Research Fellow in 2011. His research interests include terahertz optoelectronics, quantum cascade lasers, and terahertz imaging techniques.
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