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Languages : en
Pages : 8
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Book Description
Detection and identification of gas species using tunable laser diode laser absorption spectroscopy has been performed using vertical cavity surface emitting lasers (VCSEL). Two detection methods are compared: direct absorbance and wavelength modulation spectroscopy (WMS). In the first, the output of a DC-based laser is directly monitored to detect for any quench at the targeted specie wavelength. In the latter, the emission wavelength of the laser is modulated by applying a sinusoidal component on the drive current of frequency?, and measuring the harmonics component (2?) of the photo-detected current. This method shows a better sensitivity measured as signal to noise ratio, and is less susceptible to interference effects such as scattering or fouling. Gas detection was initially performed at room temperature and atmospheric conditions using VCSELs of emission wavelength 763 nm for oxygen and 1392 nm for water, scanning over a range of approximately 10 nm, sufficient to cover 5-10 gas specific absorption lines that enable identification and quantization of gas composition. The amplitude and frequency modulation parameters were optimized for each detected gas species, by performing two dimensional sweeps for both tuning current and either amplitude or frequency, respectively. We found that the highest detected signal is observed for a wavelength modulation amplitude equal to the width of the gas absorbance lines, in good agreement with theoretical calculations, and for modulation frequencies below the time response of the lasers (
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Category :
Languages : en
Pages : 8
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Book Description
Detection and identification of gas species using tunable laser diode laser absorption spectroscopy has been performed using vertical cavity surface emitting lasers (VCSEL). Two detection methods are compared: direct absorbance and wavelength modulation spectroscopy (WMS). In the first, the output of a DC-based laser is directly monitored to detect for any quench at the targeted specie wavelength. In the latter, the emission wavelength of the laser is modulated by applying a sinusoidal component on the drive current of frequency?, and measuring the harmonics component (2?) of the photo-detected current. This method shows a better sensitivity measured as signal to noise ratio, and is less susceptible to interference effects such as scattering or fouling. Gas detection was initially performed at room temperature and atmospheric conditions using VCSELs of emission wavelength 763 nm for oxygen and 1392 nm for water, scanning over a range of approximately 10 nm, sufficient to cover 5-10 gas specific absorption lines that enable identification and quantization of gas composition. The amplitude and frequency modulation parameters were optimized for each detected gas species, by performing two dimensional sweeps for both tuning current and either amplitude or frequency, respectively. We found that the highest detected signal is observed for a wavelength modulation amplitude equal to the width of the gas absorbance lines, in good agreement with theoretical calculations, and for modulation frequencies below the time response of the lasers (
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Languages : en
Pages : 1
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Languages : en
Pages :
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Compact tunable optical cavities are provided for in-situ NIR spectroscopy. MEMS-tunable VCSEL platforms represents a solid foundation for a new class of compact, sensitive and fiber compatible sensors for fieldable, real-time, multiplexed gas detection systems. Detection limits for gases with NIR cross-sections such as O.sub. 2, CH.sub. 4, CO.sub.x and NO.sub.x have been predicted to approximately span from 10.sup.ths to 10s of parts per million. Exemplary oxygen detection design and a process for 760 nm continuously tunable VCSELS is provided. This technology enables in-situ self-calibrating platforms with adaptive monitoring by exploiting Photonic FPGAs.
Author: Jia Chen
Publisher:
ISBN: 9783941650305
Category :
Languages : en
Pages : 150
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Author:
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Category :
Languages : en
Pages : 6
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We report on a novel sensing technique combining photonics and microelectromechanical systems (MEMS) for the detection and monitoring of gas emissions for critical environmental, medical, and industrial applications. We discuss how MEMS-tunable vertical-cavity surface-emitting lasers (VCSELs) can be exploited for in-situ detection and NIR spectroscopy of several gases, such as O2, N2O, CO(subscript x), CH4, HF, HCl, etc., with estimated sensitivities between 0.1 and 20 ppm on footprints (almost equal to)10−3 mm3. The VCSELs can be electrostatically tuned with a continuous wavelength shift up to 20 nm, allowing for unambiguous NIR signature determination. Selective concentration analysis in heterogeneous gas compositions is enabled, thus paving the way to an integrated optical platform for multiplexed gas identification by bandgap and device engineering. We will discuss here, in particular, our efforts on the development of a 760 nm AlGaAs based tunable VCSEL for O2 detection.
Author: Babu Dayal Padullaparthi
Publisher: John Wiley & Sons
ISBN: 1119782198
Category : Technology & Engineering
Languages : en
Pages : 356
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Book Description
A hands-on reference to the technical, commercial, and industrial aspects of VCSEL technology In VCSEL Industry: Communication and Sensing, a team of distinguished researchers and manufacturing professionals deliver a thorough and practical reference guide to vertical-cavity surface-emitting lasers (VCSELs) for young entrepreneurs, investors, venture capitalists, and researchers. The authors offer comprehensive descriptions of the technology involved, as well as a robust exploration of the industry and commercial landscape in which VCSELs exist. The book contains numerous illustrations and schematics of the anatomy of VCSEL product developments and an insightful discussion of the proliferation of VCSELs in photonics and optics. There is also a dedicated section on photoreceivers used for VCSEL-based data communications and sensing. VCSEL Industry: Communication and Sensing provides readers with an accessible, commercial perspective of an important technology while offering just enough technical detail to make sense of the subject. The book also includes: A thorough introduction to VCSELs, including discussions of semiconductor lasers, materials, wavelengths, and why VCSELs are attractive for photonics applications Comprehensive explorations of the VCSEL industry, including market demands, an industry landscape, descriptions of commercial products based on VCSELs, and business models Practical discussions of VCSELs for data communication, including high-speed VCSELs, gain and parasitic effects on bandwidth and speed, and form factors and standards In-depth examinations of VCSEL arrays for sensing, including high-power VCSELs in consumer electronics Perfect for early-career researchers, engineers, entrepreneurs, investors, and managers, VCSEL Industry: Communication and Sensing will also prove to be an invaluable addition to the libraries of executives from across the semiconductor industry.
Author: Yufei Ma
Publisher: MDPI
ISBN: 3039283987
Category : Technology & Engineering
Languages : en
Pages : 278
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Book Description
Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.
Author:
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ISBN:
Category : Chemistry
Languages : en
Pages : 2692
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Category : Electrical engineering
Languages : en
Pages : 1360
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Category : Optics
Languages : en
Pages : 760
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