Performance Characteristics of a Compact Widely Tunable External Cavity Quantum Cascade Laser

Optical spectroscopy has a broad scientific basis in chemistry, physics, and material science, with diverse applications in medicine, pharmaceuticals, agriculture, and environmental monitoring. Fourier transform infrared (FTIR) spectrometers and tunable laser spectrometers (TLS) are key devices for measuring optical spectra. Superior performance in terms of sensitivity, selectivity, accuracy, and resolution is required for applications in gas sensing. This review deals with gas measurement based on either direct optical absorption spectroscopy or photoacoustic spectroscopy. Both approaches are applicable to FTIR spectroscopy or TLS. In photoacoustic spectroscopy, cantilever-based photoacoustic spectroscopy is focused due its high performance. A literature survey is conducted revealing the recent technological advances. Theoretical fundamental detection limits are derived for TLS and FTIR, considering both direct absorption and photoacoustic spectroscopies. A theoretical comparison reveals which technology performs better. The minimum normalized absorption coefficient and normalized noise equivalent absorption coefficient appear as key parameters for this comparison. For TLS-based systems, direct absorption spectroscopy is found to be the best for lower laser power and longer path length. For FTIR-based systems, direct absorption is found to be the best for low temperature sources, higher spectrometer throughput, faster mirror velocity, and longer gas cells.

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“…[ 34–38 ] On the other hand, the linewidth of gases is a few

{\rm{GHz}}

at atmospheric pressure, [ 32,35,39–41 ] while at reduced pressure linewidths can reach tenths of

{\rm{MHz}}

. [ 42,43 ] Thus, the laser linewidth is much smaller than the gas linewidth.…”

Section: Tunable Diode Laser Systemmentioning

confidence: 99%

Direct Absorption and Photoacoustic Spectroscopy for Gas Sensing and Analysis: A Critical Review

Fathy

Sabry

Hunter

et al. 2022

Laser & Photonics Reviews

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“…More recently, quantum cascade lasers (58,59) with wide tuning ranges in the infrared region between 3 μm and 24 μm have been developed and used for trace gas analysis of a variety of environmentally relevant gases (e.g., CO, CO 2 , methane, and formaldehyde) and medically relevant gases (e.g., nitrogen monoxide, CO, CO 2 , ethane, and CS 2 ), which are also important in spacecraft air quality and planetary atmospheric science (59)(60)(61)(62)(63)(64). The wide tunability of the quantum cascade lasers is enabled through the use of so-called external cavities: Additional gratings are used as an end mirror of the laser cavity.…”

Section: R Ementioning

confidence: 99%

“…can be tuned across the entire bandwidth of the quantum cascade laser chip. The detection limits for the different gases in mixtures are in the low parts-per-billion or even parts-per-trillion range (59,(62)(63)(64). Instruments are commercially available from, for instance, Daylight Solutions, Inc. (Poway, California) (63,64).…”

Section: R Ementioning

confidence: 99%

Adaptive Microsensor Systems

Gutierrez‐Osuna

Hierlemann

2010

Annual Rev. Anal. Chem.

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We provide a broad review of approaches for developing chemosensor systems whose operating parameters can adapt in response to environmental changes or application needs. Adaptation may take place at the instrumentation level (e.g., tunable sensors) and at the data-analysis level (e.g., adaptive classifiers). We discuss several strategies that provide tunability at the device level: modulation of internal sensing parameters, such as frequencies and operation voltages; variation of external parameters, such as exposure times and catalysts; and development of compact microanalysis systems with multiple tuning options. At the data-analysis level, we consider adaptive filters for change, interference, and drift rejection; pattern classifiers that can adapt to changes in the statistical properties of training data; and active-sensing techniques that can tune sensing parameters in real time. We conclude with a discussion of future opportunities for adaptive sensing in wireless distributed sensor systems.

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Performance characteristics of a continuous-wave compact widely tunable external cavity interband cascade lasers

Caffey¹,

Day²,

Kim³

et al. 2010

Opt. Express

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Performance Characteristics of a Compact Widely Tunable External Cavity Quantum Cascade Laser

Cited by 3 publications

References 9 publications

Direct Absorption and Photoacoustic Spectroscopy for Gas Sensing and Analysis: A Critical Review

Direct Absorption and Photoacoustic Spectroscopy for Gas Sensing and Analysis: A Critical Review

Adaptive Microsensor Systems

Performance characteristics of a continuous-wave compact widely tunable external cavity interband cascade lasers

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