Recovery of Absolute Gas Absorption Line Shapes Using Tuneable Diode Laser Spectroscopy with Wavelength Modulation ¿ Part I: Theoretical Analysis

Stewart, George; Johnstone, Walter; Bain, James R. P.; Ruxton, Keith; Duffin, Kevin L.

doi:10.1109/jlt.2011.2107312

Cited by 41 publications

(43 citation statements)

References 47 publications

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“…Here we cite the previous research finding [27], [28], the second harmonic signal detected by the lock-in amplifier concludes three components: 2) Two further components generated by the RAM, which are proportional to −0.5α 0 CLb 1 I (ν 1 ) at phase -ϕ and −0.5α 0 CLb 3 I (ν 1 ) at phase −3ϕ, respectively. Although carefully choosing the lock-in detection phase is an effective mean to eliminate the RAM [22], it is clear that the two further components generated by RAM cannot be cancelled by single choice of lock-in phase at the same time.…”

Section: Application In Tdlas-wms For Ram Reduction a Theorymentioning

confidence: 98%

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

et al. 2015

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A continuously wavelength-tunable light source with constant-power output is presented. The unwanted optical power modulation companying with the wavelength modulation of the distributed feedback laser diode by the injection current is successfully offset by the external amplitude modulation of electro-optic modulator. The optical power stability has been experimentally demonstrated better than 1.2% in a wavelengthtunable range of 0.876 cm −1 . The background baseline appearing in the direct absorption spectrum can be removed with the new light source. Not only that, the spectral distortion of the second harmonic signal caused by residual-amplitude modulation can also be largely eliminated. Experimental results have shown that the new light source is more suitable to be served as a pure wavelength-tuning reference source for different modes of spectroscopic measurement.

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Section: Application In Tdlas-wms For Ram Reduction a Theorymentioning

confidence: 98%

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

et al. 2015

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“…Both these methods were initially limited to low m-values that were well below the optimum value of m = 2 for 1f WMS. Recently, however, a way to overcome this problem using Fourier analysis of the Lortenzian line shape has been demonstrated [21,22], which makes these approaches attractive for industrial applications where one would aim to operate at high m-values to maximize the received signal strength.…”

Section: Calibration-free Detection Techniquesmentioning

confidence: 99%

Rapid detection of methane, carbon dioxide and ammonia for harsh environments using tunable doide laser spectroscopy

Upadhyay¹,

Dighe²,

Chakraborty³

2013

2013 International Conference on Microwave and Photonics (ICMAP)

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This paper reports time-varying and simultaneous detection of the pressure and concentration, of hazardous gases such as methane, carbon dioxide and ammonia using tunable diode laser spectroscopy (TDLS). The concentration and pressure of the gases is extracted with a time resolution of 10s, which makes this method useful in applications that require in situ, real-time measurements of several gases. A calibration-free wavelength modulation spectroscopy (WMS) approach known as the Residual Amplitude Modulation (RAM) method has been used at a modulation frequency when intensity modulation (IM)is at phase-quadrature to the frequency modulation (FM). TDLS offers the dual advantage of remote detection of gases and quantification of gas parameters. This makes them ideally suited to hazardous environments such as coal mines.

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“…1) and produced a very sensitive sensor using 2f spectroscopy [3], none of which was ever published -we were a company after all, and not a university. The topic of gas absorption line shapes remains important to this day [4]. I soon determined that I needed a PhD and began to look around.…”

Section: The Road To Kentmentioning

confidence: 99%

Staying coherent after kent: From optical communications to biomedical optics

Sampson

2011

Photonic Sens

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In this paper, an overview of author's research is presented, commencing at the University of Kent under Prof. David A. Jackson. Early research in short optical pulses and fiber-optic delay-line digital correlators led to optical communications research in code-division multiple access networking. This research was based on broadband incoherent light, and this theme continued with research into spectrum-sliced wavelength-division multiplexing. In shifting from photonics research to biomedical optics and biophotonics in the late 1990s, the emphasis on exploiting broadband light continued with research in optical coherence tomography, amongst other topics. In addition to the research outcomes, how these outcomes were attained is described, including mention of the exceptional contributions of many of my colleagues.

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Recovery of Absolute Gas Absorption Line Shapes Using Tuneable Diode Laser Spectroscopy with Wavelength Modulation ¿ Part I: Theoretical Analysis

Cited by 41 publications

References 47 publications

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

Continuously Wavelength-Tunable Light Source With Constant-Power Output for Elimination of Residual Amplitude Modulation

Rapid detection of methane, carbon dioxide and ammonia for harsh environments using tunable doide laser spectroscopy

Staying coherent after kent: From optical communications to biomedical optics

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