Tunable Diode Laser Absorption Spectroscopy

TDLAS exploits the rotational vibrational absorption features of gases for laser-based trace gas detection. Sometimes, it is referred to as TDLS, TLS, TLAS or (with a reference) even as TDLARS.

TDLAS is a very strong tool for highly selective and sensitive measurements. It enables:

• sensitive detection of ppm to ppb (or even ppt!) level concentrations
• in situ measurements
• contactless techniques
• operation at or above room temperature
• measurement of sticky gases
• portable gas detectors

TDLAS is one of the most sensitive, selective and robust technologies for trace gas monitoring. It is based on the Lambert-Beer law which states a logarithmic relation between the

• transmission of light through a gas
• product of the attenuation coefficient of the gas
• distance the light travels through the gas

When a gas has an absorption feature at a specific wavelength, the transmitted intensity declines exponentially with:

I(ν,t) = I₀(ν) e^{-S(T) g(ν,ν₀) n L}

With n being the number density of the molecular absorbers, I₀(ν) the initial laser intensity and I(ν,t) the intensity detected after the probe with an absorption length L.

The absorption line profile is characterized by the temperature-dependent, spectrally integrated line strength S(T), and the normalized (area=1) shape function g(ν,ν₀), which is centered at the wavelength ν₀.

(Source: #47 High-speed tunable diode laser absorption spectroscopy for sampling-free in-cylinder water vapor concentration measurements in an optical IC engine;
O. Witzel, A. Klein, S. Wagner, C. Meffert, C. Schulz, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 521-532.)

Compared to other highly sensitive technologies, such as gas chromatography TDLAS instruments show

• high selectivity
• low cost of ownership
• fail-safe operation

TDLAS is carried out in form of e. g.:

• direct absorption spectroscopy
• 2f spectroscopy
• cavity enhanced spectroscopy (CRDS)
• light detection and ranging techniques (LIDAR)
• photo acoustic spectroscopy (PAS)

#3 Gas monitoring in the process industry using diode laser spectroscopy;
I. Linnerud, P.Kaspersen, T. Jaeger, Appl. Phys. B 67, 1998, pp. 297-305.

#10 Continuous wave, distributed feedback diode laser based sensor for trace-gas detection of ethane;
K. Krzempek, R. Lewicki, L. Naehle, M. Fischer, J. Koeth, S. Belahsene, Y. Rouillard, L. Worschech, F.K. Tittel, Appl. Phys. B 106, 2, 2012, pp 251-255.

#15 Scanned-wavelength-modulation spectroscopy near 2.5 µm for H₂O and temperature in a hydrocarbon-fueled scramjet combustor;
C. S. Goldenstein, I. A. Schultz, R. M. Spearrin, J. B. Jeffries, R.K. Hanson, Appl. Phys. B, 116, 3, Sept 2014, pp 717-727.

#16 Diode laser measurements of linestrength and temperature-dependent lineshape parameters of H₂O-, CO₂-, and N₂-perturbed H₂O transitions near 2474 and 2482 nm;
C.S. Goldenstein, J.B. Jeffries, R.K. Hanson, J. of Quantitative Spectr. & Radiative Transfer 130, 2013, pp. 100–111.

#17 Wavelength-modulation spectroscopy near 2.5 µm for H₂O and temperature in high-pressure and -temperature gases;
C.S. Goldenstein, R.M. Spearrin, J.B. Jeffries, R.K. Hanson, Appl. Phys. B, 116, 3, Sept 2014, pp 705-716.

#28 In situ combustion measurements of H₂O and temperature near 2.5 µm using tunable diode laser absorption;
A. Farooq, J.B Jeffries, R.K Hanson, Meas. Sci. Technol., 19, 2008, 075604, pp. 11.

#32 Single-frequency Sb-based distributed-feedback lasers emitting at 2.3 µm above room temperature for application in tunable diode laser absorption spectroscopy;
A. Salhi, D. Barat, D. Romanini, Y. Rouillard, A. Ouvrard, R. Werner, J. Seufert, J. Koeth, A. Vicet, A. Garnache, Appl. Opt., 45, 20., pp. 4957-4965.

#35 TDLAS-based sensors for in situ measurement of syngas composition in a pressurized, oxygen-blown, entrained flow coal gasifier;
R. Sur, K. Sun, J.B. Jeffries, R.K. Hanson, R.J. Pummill, T. Waind, D.R. Wagner, K.J. Whitty, Appl. Phys. B, 116, 1, 2014, pp. 33-42.

#43 Chemical analysis of surgical smoke by infrared laser spectroscopy;
Michele Gianella, Markus W. Sigrist, Appl. Phys. B, 109, 3, Nov. 2012, pp. 485-496.

#46 TDLAS-based open-path laser hygrometer using simple reflective foils as scattering targets;
A. Seidel, S. Wagner, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 497-504.

#47 High-speed tunable diode laser absorption spectroscopy for sampling-free in-cylinder water vapor concentration measurements in an optical IC engine;
O. Witzel, A. Klein, S. Wagner, C. Meffert, C. Schulz, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 521-532.

#48 Absolute, spatially resolved, in situ CO profiles in atmospheric laminar counter-flow diffusion flames using 2.3 µm TDLAS;
S. Wagner, M. Klein, T. Kathrotia, U. Riedel, T. Kissel, A. Dreizler, V. Ebert, Appl. Phys. B, 109, 3, Nov. 2012, pp. 533-540.

#52 Antireflection-coated blue GaN laser diodes in an external cavity and Doppler-free indium absorption spectroscopy;
L. Hildebrandt, R. Knispel, S. Stry, J.R. Sacher, F. Schael, Appl. Opt., 42, No. 12, 2003, pp. 2110-2118.

#56 Widely tunable quantum cascade lasers with coupled cavities for gas detection;
P. Fuchs, J. Seufert, J. Koeth, J. Semmel, S. Hoefling, L. Worschech, A. Forchel, App. Phys. Lett., 97, 2010, 181111.

#62 High-sensitivity interference-free diagnostic for measurement of methane in shock tubes;
R. Sur, S. Wang, K. Sun, D. F. Davidson, J. B. Jeffries, R. K. Hanson, J. of Quant. Spectrosc. and Rad. Transfer, Vol. 156, May 2015, pp. 80–87.

#65 H₂O temperature sensor for low-pressure flames using tunable Diode laser Absorption near 2.9 µm;
S. Li, A. Farooq, R.K. Hanson, Meas. Sci. Technol., 22, 2011, pp. 125301-125311.

#67 New Opportunities in Mid-Infrared Emission Control;
P. Geiser, Sensors, 2015, pp. 22724-22736.

#68 Field laser applications in industry and research;
F. D'Amato, A. Fried, App. Phys. B, 2015, 119, pp. 1-2.

#69 A quartz-enhanced photoacoustic sensor for H₂S trace-gas detection at 2.6µm;
S. Viciani, M. Siciliani de Cumis, S. Borri, P. Patimisco, A. Sampaolo, G. Scamarcio, P. De Natale, F. D'Amato, V. Spagnolo, App. Phys. B, 2015, 119, pp. 21-27.

#70 In situ H₂O and temperature detection close to burning biomass pellets using calibration-free wavelength modulation spectroscopy;
Z. Qu, F.M. Schmidt, App. Phys. B, 2015, 119, pp. 45-53.

#71 Novel utilisation of a circular multi-reflection cell applied to materials ageing experiments;
D.A. Knox, A.K. King, E.D. McNaghten, S.J. Brooks, P.A. Martin, S.M. Pimblott, App. Phys. B, 2015, 119, pp. 55-64.

#72 TDLAS-based NH₃ mole fraction measurement for exhaust diagnostics during selective catalytic reduction using a fiber-coupled 2.2-µm DFB Diode laser;
F. Stritzke, O. Diemel, S. Wagner, App. Phys. B, 2015, 119, pp. 143-152.

#73 Time-multiplexed open-path TDLAS spectrometer for dynamic, sampling-free, Interstitial H₂¹⁸O and H₂¹⁶O vapor detection in ice clouds;
B. Kuehnreich, S. Wagner, J.C. Habig, O. Moehler, H. Saathoff, V. Ebert, App. Phys. B, 2015, 119, pp. 177-187.

#78 Ppb-level formaldehyde detection using a CW room-temperature interband cascade laser and a miniature dense pattern multipass gas cell;
L. Dong,Y. Yu,.C. Li, S. So, F. Tittel, Optics Express Vol. 23, Issue 15, 2015, pp. 19821-19830.

# 84 Optical gas sensing: a review;
J. Hodgkinson, R. P. Tatam, Measurement Science and Technology, Vol. 24, No. 1, 2013

# 85 Frequency modulation characteristics for interband cascade lasers emitting at 3 µm;
J. Li, Z. Du, Y. An, Appl. Phys. B, 2015, 121:7–17.

#87 Optical‑feedback cavity‑enhanced absorption spectroscopy with an interband cascade laser: application to SO₂ trace analysis;
L. Richard, I. Ventrillard, G. Chau, K. Jaulin, E. Kerstel, D. Romanini, Appl. Phys. B, 2016, 122:247.

#90 Optical feedback cavity-enhanced absorption spectroscopy with a 3.24 µm interband cascade laser;
K. M. Manfred, G. A. D. Ritchie, N. Lang, J. Roepcke, J. H. van Helden, Appl. Phys. Lett. 106, 2015, 221106.

#93 Interband cascade laser-based optical transfer standard for atmospheric carbon monoxide measurements;
J. A. Nwaboh, Z. Qu, O. Werhahn and V. Ebert, App. Optics, Vol. 56, No. 11, April 10, 2017, pp. E84-E93.

#94 Compact optical probe for flame temperature and carbon dioxide using interband cascade laser absorption near 4.2 μm;
J. J. Girard, R. M. Spearrin, C. S. Goldenstein, R. K. Hanson, Elsevier, Combustion and Flame, Vol. 178, April 2017, pp. 158 – 167.

#96 Fiber-coupled 2.7 μm laser absorption sensor for CO₂ in harsh combustion environments;
R. M. Spearrin, C. S. Goldenstein, J. B. Jeffries and R. K. Hanson, Meas. Sci. Technol. 24, April 2013, 055107.

#100 Multiheterodyne spectroscopy using interband cascade lasers;
L. A. Sterczewski, J. Westberg, C. L. Patrick, C. S. Kim, M. Kim, C. L. Canedy, W. W. Bewley, C. D. Merritt, I. Vurgaftman, J. R. Meyer and G. Wysocki, Opt. Eng. 57(1), 011014, Jan. 2018.

# 157 MHz laser absorption spectroscopy via diplexed RF modulation for pressure, temperature, and species in rotating detonation rocket flows;
A. Nair, D. Lee, D. I. Pineda, J. Kriesel, W. A. Hargus Jr., J. W. Bennewitz, S. A. Danczyk, R. M. Spearrin, Appl. Physics B, Lasers and Optics, 126, 2020.

# 160 Narrow linewidth characteristics of interband cascade lasers;
Y. Deng, B.-B. Zhao, X.-G. Wang, C. Wang, Appl. Phys. Lett., 116, 2020, 201101-5.