Optimizing Gas Sensors Based on Quantum Cascade Lasers and Photonic Bandgap Hollow Waveguides

Young, Christina; Hartwig, S.; Lambrecht, A.; Kim, Seong-Soo; Mizaikoff, Boris

doi:10.1109/icsens.2007.4388660

Cited by 11 publications

(8 citation statements)

References 11 publications

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“…Coiling smaller diameter waveguides has been demonstrated to reduce the overall form factor, however, at the expense of sensitivity and robustness. − Moreover, there are, to the best of our knowledge, no long-term studies reported that demonstrate how the internal mechanical bending stresses imposed onto structural materials and optical coatings in a coiled conventional HWG affect the overall lifetime of the HWG. Tubular devices depend on wet-chemistry for applying internal coatings, which significantly limits the coating options.…”

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confidence: 99%

Substrate-Integrated Hollow Waveguides: A New Level of Integration in Mid-Infrared Gas Sensing

et al. 2013

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A new generation of hollow waveguide (HWG) gas cells of unprecedented compact dimensions facilitating low sample volumes suitable for broad- and narrow-band mid-infrared (MIR; 2.5-20 μm) sensing applications is reported: the substrate-integrated hollow waveguide (iHWG). iHWGs are layered structures providing light guiding channels integrated into a solid-state substrate material, which are competitive if not superior in performance to conventional leaky-mode fiber optic silica HWGs having similar optical pathlengths. In particular, the provided flexibility in device and optical design and the wide variety of manufacturing strategies, substrate materials, access to the optical channel, and optical coating options highlight the advantages of iHWGs in terms of robustness, compactness, and cost-effectiveness. Finally, the unmatched modularity of this novel waveguide approach facilitates tailoring iHWGs to almost any kind of gas sensor technology providing adaptability to the specific demands of a wide range of sensing scenarios. Device fabrication is demonstrated for the example of a yin-yang-shaped gold-coated iHWG fabricated within an aluminum substrate with a footprint of only 75 mm × 50 mm × 12 mm (L × W × H), yet providing a nominal optical absorption path length of more than 22 cm. The analytical utility of this device for advanced MIR gas sensing applications is demonstrated for the gaseous constituents butane, carbon dioxide, cyclopropane, isobutylene, and methane.

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Substrate-Integrated Hollow Waveguides: A New Level of Integration in Mid-Infrared Gas Sensing

et al. 2013

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“…Modulated IR radiation periodically heats the sample gas, thereby producing a pressure wave detectable at acoustic frequencies as a function of analyte concentration. interaction path length, and radiation losses from bending the waveguide has to be determined [119].…”

Section: B Transducers 1) Hollow Core Waveguides Versus Conventional Gasmentioning

confidence: 99%

Potential and Challenges for Mid-Infrared Sensors in Breath Diagnostics

et al. 2010

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Exhaled breath contains more than 1000 constituents at trace level concentrations, with a wide variety of these compounds potentially serving as biomarkers for specific diseases, physiologic status, or therapeutic progress. Some of the compounds in exhaled breath (EB) are well studied, and their relationship with disease pathologies is well established. However, molecularly specific analysis of such biomarkers in EB at clinically relevant levels remains an analytical and practical challenge due to the low levels of such biomarkers frequently below the ppb (v/v) range in EB. In this contribution, mid-infrared (MIR) spectroscopic sensing techniques are reviewed for potential application in breath diagnostics. While the spectral regime from 3-20 m has already been utilized for fundamental studies on breath analysis, significant further improvements are in demand for substantiating MIR spectroscopy and sensing techniques as a suitable candidate for clinically deployable breath analyzers. Several advantageous features including inherent molecular selectivity, real-time monitoring capability, comparable ease of operation, potentially low costs, and a compact device footprint promise reliable optical diagnostics in the MIR. Hence, while the application of MIR spectroscopy and sensing systems to breath analysis yet appear in their infancy, recent progress on advanced MIR light sources, waveguides, and device concepts forecasts next-generation optical sensing platforms suitable for addressing the challenges of in situ breath diagnostics.

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“…Details of the measurements are described elsewhere. 17 Caused by the photonic structure the Omniguide ® -fiber is only transmitting between 900 -1050 cm -1 . To compare with the QCL measurements the attenuations were determined at 10.34μm, and 50cm long straight fiber sections were used.…”

Section: Transmission Measurements With Thermal Emittersmentioning

confidence: 99%

Hollow fibers for compact infrared gas sensors

et al. 2008

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Hollow fibers can be used for compact infrared gas sensors. The guided light is absorbed by the gas introduced into the hollow core. High sensitivity and a very small sampling volume can be achieved depending on fiber parameters i.e. attenuation, flexibility, and gas exchange rates. Different types of infrared hollow fibers including photonic bandgap fibers were characterized using quantum cascade lasers and thermal radiation sources. Obtained data are compared with available product specifications. Measurements with a compact fiber based ethanol sensor are compared with a system simulation. First results on the detection of trace amounts of the explosive material TATP using hollow fibers and QCL will be shown

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Optimizing Gas Sensors Based on Quantum Cascade Lasers and Photonic Bandgap Hollow Waveguides

Cited by 11 publications

References 11 publications

Substrate-Integrated Hollow Waveguides: A New Level of Integration in Mid-Infrared Gas Sensing

Substrate-Integrated Hollow Waveguides: A New Level of Integration in Mid-Infrared Gas Sensing

Potential and Challenges for Mid-Infrared Sensors in Breath Diagnostics

Hollow fibers for compact infrared gas sensors

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