362
A. L. Chakraborty and A. Roy
50. K. Duffin, A.J. McGettrick, W. Johnstone, G. Stewart, D.G. Moodie, Tunable diode-laser spectroscopy with wavelength modulation: a calibration-free approach to the recovery of absolute
gas absorption line shapes. J. Lightw. Technol. 25,3114–3125 (2007) (IEEE)
51. A.J. McGettrick, K. Duffin, W. Johnstone, G. Stewart, D.G. Moodie, Tunable diode laser
spectroscopy with wavelength modulation: a phasor decomposition method for calibrationfree measurements of gas concentration and pressure. J. Lightwave Technol. 26, 432–440
(2008) (IEEE)
52. A. Upadhyay, M. Lengden, D. Wilson, G.S. Humphries, A.P. Crayford, D.G. Pugh, M.P. Johnson, G. Stewart, W. Johnstone, A new RAM normalized 1$f$-WMS technique for the measurement of gas parameters in harsh environments and a comparison with 2f/1f$. IEEE Photon. J.
10, 1–11 (2018)
53. W.Y. Peng, C.L. Strand, R.K. Hanson, Analysis of laser absorption gas sensors employing
scanned-wavelength modulation spectroscopy with 1f-phase detection. Appl. Phys. B 126, 17
(2019)
54. J.R.P. Bain, W. Johnstone, K. Ruxton, G. Stewart, M. Lengden, K. Duffin, Recovery of
absolute gas absorption line shapes using tunable diode laser spectroscopy with wavelength
modulation—Part 2: experimental investigation. J. Lightwave Technol. 29, 987–996 (2011)
(IEEE)
55. G. Stewart, W. Johnstone, J.R.P. Bain, K. Ruxton, K. Duffin, Recovery of absolute gas absorption line shapes using tunable diode laser spectroscopy with wavelength modulation—Part I:
theoretical analysis. J. Lightwave Technol. 29, 811–821 (2011) (IEEE)
56. A. Upadhyay, A.L. Chakraborty, Residual amplitude modulation method implemented at the
phase quadrature frequency of a 1650-nm laser diode for line shape recovery of methane. IEEE
Sens. J. 15, 1153–1160 (2015)
57. A.L. Chakraborty, K. Ruxton, W. Johnstone, M. Lengden, K. Duffin, Elimination of residual
amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an
optical fiber delay line. Opt. Express 17, 9602–9607 (2009) (Optical Society of America)
58. A.L. Chakraborty, K. Ruxton, W. Johnstone, Influence of the wavelength-dependence of fiber
couplers on the background signal in wavelength modulation spectroscopy with RAM-nulling.
Opt. Express 18, 267–280 (2010) (Optical Society of America)
59. A.L. Chakraborty, K. Ruxton, W. Johnstone, Suppression of intensity modulation contributions
to signals in second harmonic wavelength modulation spectroscopy. Opt. Lett. 35, 2400–2402
(2010) (Optical Society of America)
60. H. Li, G.B. Rieker, X. Liu, J.B. Jeffries, R.K. Hanson, Extension of wavelength-modulation
spectroscopy to large modulation depth for diode laser absorption measurements in highpressure gases. Appl. Opt. 45, 1052–1061 (2006) (Optical Society of America)
61. A.L. Chakraborty, Calibration-free wavelength modulation spectroscopy with elimination of
residual amplitude modulation. Ph.D. thesis, University of Strathclyde, Glasgow, UK, 2010
62. A. Roy A.L. Chakraborty, Intensity modulation-normalized calibration-Free 1f and 2f wavelength modulation spectroscopy. IEEE Sens. J. 20, 12691–12701 (2020)
63. P. Werle, R. Mücke, F. Slemr, The limits of signal averaging in atmospheric trace-gas monitoring
by tunable diode-laser absorption spectroscopy (TDLAS). Appl. Phys. B 57, 131–139 (1993)
64. Y. Bidaux, A. Bismuto, P. Patimisco, A. Sampaolo, T. Gresch, G. Strubi, S. Blaser, F.K. Tittel,
V. Spagnolo, A. Muller, J. Faist, Mid infrared quantum cascade laser operating in pure amplitude
modulation for background-free trace gas spectroscopy. Opt. Express 24, 26464–26471 (2016)
(Optical Society of America)
65. A. Shehzad, P. Brochard, R. Matthey, S. Blaser, T. Gresch, R. Maulini, A. Muller, T. Südmeyer,
S. Schilt, Electrically-driven pure amplitude and frequency modulation in a quantum cascade
laser. Opt. Express 26, 12306–12317 (2018) (Optical Society of America)
A. L. Chakraborty and A. Roy
50. K. Duffin, A.J. McGettrick, W. Johnstone, G. Stewart, D.G. Moodie, Tunable diode-laser spectroscopy with wavelength modulation: a calibration-free approach to the recovery of absolute
gas absorption line shapes. J. Lightw. Technol. 25,3114–3125 (2007) (IEEE)
51. A.J. McGettrick, K. Duffin, W. Johnstone, G. Stewart, D.G. Moodie, Tunable diode laser
spectroscopy with wavelength modulation: a phasor decomposition method for calibrationfree measurements of gas concentration and pressure. J. Lightwave Technol. 26, 432–440
(2008) (IEEE)
52. A. Upadhyay, M. Lengden, D. Wilson, G.S. Humphries, A.P. Crayford, D.G. Pugh, M.P. Johnson, G. Stewart, W. Johnstone, A new RAM normalized 1$f$-WMS technique for the measurement of gas parameters in harsh environments and a comparison with 2f/1f$. IEEE Photon. J.
10, 1–11 (2018)
53. W.Y. Peng, C.L. Strand, R.K. Hanson, Analysis of laser absorption gas sensors employing
scanned-wavelength modulation spectroscopy with 1f-phase detection. Appl. Phys. B 126, 17
(2019)
54. J.R.P. Bain, W. Johnstone, K. Ruxton, G. Stewart, M. Lengden, K. Duffin, Recovery of
absolute gas absorption line shapes using tunable diode laser spectroscopy with wavelength
modulation—Part 2: experimental investigation. J. Lightwave Technol. 29, 987–996 (2011)
(IEEE)
55. G. Stewart, W. Johnstone, J.R.P. Bain, K. Ruxton, K. Duffin, Recovery of absolute gas absorption line shapes using tunable diode laser spectroscopy with wavelength modulation—Part I:
theoretical analysis. J. Lightwave Technol. 29, 811–821 (2011) (IEEE)
56. A. Upadhyay, A.L. Chakraborty, Residual amplitude modulation method implemented at the
phase quadrature frequency of a 1650-nm laser diode for line shape recovery of methane. IEEE
Sens. J. 15, 1153–1160 (2015)
57. A.L. Chakraborty, K. Ruxton, W. Johnstone, M. Lengden, K. Duffin, Elimination of residual
amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an
optical fiber delay line. Opt. Express 17, 9602–9607 (2009) (Optical Society of America)
58. A.L. Chakraborty, K. Ruxton, W. Johnstone, Influence of the wavelength-dependence of fiber
couplers on the background signal in wavelength modulation spectroscopy with RAM-nulling.
Opt. Express 18, 267–280 (2010) (Optical Society of America)
59. A.L. Chakraborty, K. Ruxton, W. Johnstone, Suppression of intensity modulation contributions
to signals in second harmonic wavelength modulation spectroscopy. Opt. Lett. 35, 2400–2402
(2010) (Optical Society of America)
60. H. Li, G.B. Rieker, X. Liu, J.B. Jeffries, R.K. Hanson, Extension of wavelength-modulation
spectroscopy to large modulation depth for diode laser absorption measurements in highpressure gases. Appl. Opt. 45, 1052–1061 (2006) (Optical Society of America)
61. A.L. Chakraborty, Calibration-free wavelength modulation spectroscopy with elimination of
residual amplitude modulation. Ph.D. thesis, University of Strathclyde, Glasgow, UK, 2010
62. A. Roy A.L. Chakraborty, Intensity modulation-normalized calibration-Free 1f and 2f wavelength modulation spectroscopy. IEEE Sens. J. 20, 12691–12701 (2020)
63. P. Werle, R. Mücke, F. Slemr, The limits of signal averaging in atmospheric trace-gas monitoring
by tunable diode-laser absorption spectroscopy (TDLAS). Appl. Phys. B 57, 131–139 (1993)
64. Y. Bidaux, A. Bismuto, P. Patimisco, A. Sampaolo, T. Gresch, G. Strubi, S. Blaser, F.K. Tittel,
V. Spagnolo, A. Muller, J. Faist, Mid infrared quantum cascade laser operating in pure amplitude
modulation for background-free trace gas spectroscopy. Opt. Express 24, 26464–26471 (2016)
(Optical Society of America)
65. A. Shehzad, P. Brochard, R. Matthey, S. Blaser, T. Gresch, R. Maulini, A. Muller, T. Südmeyer,
S. Schilt, Electrically-driven pure amplitude and frequency modulation in a quantum cascade
laser. Opt. Express 26, 12306–12317 (2018) (Optical Society of America)