Low-level and ultralow-volume hollow waveguide based carbon monoxide sensor

Chen, Jia; Hangauer, Andreas; Strzoda, R.; Fleischer, Maximilian; Amann, Markus‐Christian

doi:10.1364/ol.35.003577

Cited by 29 publications

(32 citation statements)

References 13 publications

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“…VCSELs have been widely used in TDLS [27]- [29] because of their low power requirement, wide tunable range and rapid tuning rate. It would be an advantage to be able to implement the RAM method using these lasers.…”

Section: Prospects Of Using the Ram Methods With Vcselsmentioning

confidence: 99%

Residual Amplitude Modulation Method Implemented at the Phase Quadrature Frequency of a 1650-nm Laser Diode for Line Shape Recovery of Methane

Upadhyay

Chakraborty

2015

IEEE Sensors J.

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This paper reports the extraction of concentration and pressure of methane using a 1650-nm laser diode operated at its phase quadrature frequency (f q ) and using the calibrationfree residual amplitude modulation (RAM) method. Although the RAM method is the simplest calibration-free technique, it has low signal levels compared with the phasor decomposition (PD) method for small values of the phase difference ψ between the laser intensity modulation and frequency modulation (FM). For the laser diode used in this paper, ψ turned out to be 90°at a very modest modulation frequency of 125.5 kHz, which is an order of magnitude lower than values reported elsewhere. The RAM signal and FM signal are at phase quadrature at this frequency and each can be fully and simultaneously recovered along a detection axis of a lock-in amplifier free from distortion by the other. The absolute absorption profile is accurately recovered with the signal-to-noise ratio (SNR) maximized for this laser. The gas parameters are extracted by fitting a Voigt line shape to the experimental data. These results show that when operating at f q , the PD method offers no advantage over the RAM method and is therefore redundant. In addition, the background RAM is eliminated by an automatic fiber-optic RAM nulling technique. Finally, the RAM method is also implemented at high values of modulation index to increase the SNR ratio. The time resolution of measurements is currently 10 s. The prospect of using the RAM method with a 2004-nm vertical cavity surface emitting laser is also explored. IndexTerms-Calibration-free, residual amplitude modulation, tunable diode laser spectroscopy, VCSEL, phasor decomposition method, methane.

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Section: Prospects Of Using the Ram Methods With Vcselsmentioning

confidence: 99%

Residual Amplitude Modulation Method Implemented at the Phase Quadrature Frequency of a 1650-nm Laser Diode for Line Shape Recovery of Methane

Upadhyay

Chakraborty

2015

IEEE Sensors J.

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“…These alternatives include, for example, tuneable diode laser absorption spectroscopy (TDLAS) and mid-IR absorption spectroscopy utilising quantum-cascade laser (QCL) sources. 22,23 While these techniques exhibit very high sensitivity, with detection limits often down to the ppbrange, they have the drawback that very often a separate laser source is required, to resonantly probe each individual species in a gas mixture. Also, one might miss unexpected constituents in a gas mixture which lie outside the wavelength range of the particular excitation laser.…”

Section: And Csontos Et Almentioning

confidence: 99%

Trace gas and dynamic process monitoring by Raman spectroscopy in metal-coated hollow glass fibres

2015

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Quantitative capillary Raman spectroscopy measurements are described, in which improved speed and sensitivity for atmospheric trace gas analysis and real-time monitoring of catalytic hydrogen-exchange reactions were demonstrated. ARTICLE accepted for publicationT.M. James et al -Raman trace gas and process monitoring using metal-coated hollow glass fibres Results on using capillary Raman spectroscopy as an approach for improving the speed, sensitivity and limit of detection for quantitative analysis of gases are reported. Specifically, its potential for trace component identification and rapid process control has been explored. Using a metal-lined hollow glass capillary configuration, its Raman signal was found to be two orders of magnitude larger than that from a conventional 90° Raman implementation. However, the actual improvement in the signal-to-noise ratio and thus the limit of detection was markedly lower, due to an increase in the fluorescence background generated in optical components in the laser beam path and the capillary body itself. Using careful, systematic suppression strategies, the signal-tonoise ratio of our capillary setup increased by a further factor of 3-4, now yielding detection limits for trace gases well below the 100 ppm level. In a "dynamic" measurement series the time evolution of catalytic gas mixing of H 2 and D 2 , to form HD, has been recorded, in which sub-mbar detection limits in sub-second recording times were achieved.

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“…For absorption spectroscopy, conventional wisdoms often treat HWG as incapable of higher accuracy measurement because majority of us spectroscopists [5][6][7], including the authors here 5 years ago, believe that HWG supports multimode inherently. However, work in references [6,7] excited HWG's higher order modes and HWG is not maintained to filter out the higher order modes, and thus noise due to multimode detection is present and needs to be alleviated.…”

Section: Experiments How Could Hwg + Qcl Sensor Achieve High Accuracy?mentioning

confidence: 99%

A field-deployable compound-specific isotope analyzer based on quantum cascade laser and hollow waveguide

Deev

2013

Quantum Sensing and Nanophotonic Devices X

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A field deployable Compound Specific Isotope Analyzer (CSIA) coupled with capillary chromatogrpahy based on Quantum Cascade (QC) lasers and Hollow Waveguide (HWG) with precision and chemical resolution matching mature Mass Spectroscopy has been achieved in our laboratory. The system could realize 0.3 per mil accuracy for 12C/13C for a Gas Chromatography (GC) peak lasting as short as 5 seconds with carbon molar concentration in the GC peak less than 0.5%. Spectroscopic advantages of HWG when working with QC lasers, i.e. single mode transmission, noiseless measurement and small sample volume, are compared with traditional free space and multipass spectroscopy methods.

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Low-level and ultralow-volume hollow waveguide based carbon monoxide sensor

Cited by 29 publications

References 13 publications

Residual Amplitude Modulation Method Implemented at the Phase Quadrature Frequency of a 1650-nm Laser Diode for Line Shape Recovery of Methane

Residual Amplitude Modulation Method Implemented at the Phase Quadrature Frequency of a 1650-nm Laser Diode for Line Shape Recovery of Methane

Trace gas and dynamic process monitoring by Raman spectroscopy in metal-coated hollow glass fibres

A field-deployable compound-specific isotope analyzer based on quantum cascade laser and hollow waveguide

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