In situ Measurement of Combustion Gas Using Terahertz Time Domain Spectroscopy Setup for Gas Phase Spectroscopy and Measurement of Solid Sample

Uno, Takeshi; Tabata, Hitoshi

doi:10.1143/jjap.49.04dl17

Cited by 14 publications

(11 citation statements)

References 30 publications

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“…THz would offer advantages of powers in excess of 1mW at ~300GHz [12], high data rates, high directivity, particulate-matter resistance, and an added advantage of point-to-point security due to this atmospheric attenuation. Other areas of THz applications are included, but not limited to: combustion gas monitors [13], art conservation [14], health care [15], gas spectroscopy [16], industrial non-destructive testing [17], chemical identification & physical security [18]. Therefore, the RTD is one key part of this core of technologies with the potential to unlock a better quality of life for many.…”

Section: Introductionmentioning

confidence: 99%

Resonant Tunnelling Diodes for next generation THz systems

Baba

Jacobs

Stevens

et al. 2018

2018 IEEE British and Irish Conference on Optics and Photonics (BICOP)

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Resonant tunnelling diodes (RTDs) are a strong candidate for future wireless communications in the THz spectrum (sub-millimetre waves), offering compact, roomtemperature operation with the potential to exceed the bit transfer rate mandated by the 12G-SDI standard, using a single wireless link. A free-space RTD emitter operating at 353GHz is described. The fabrication process consists of a dual-pass I-line photolithography & etch technique using an air bridge, allowing low resistivity ohmic contacts, and accurate control of desired device area. With extrinsic circuit elements taken into account, the intrinsic semiconductor efficiency is analysed to investigate structural improvements for radiative efficiency. Such optimised structures are presented, and then characterised after being epitaxially grown with commercially viable metal-organic vapour phase epitaxy (MOVPE) reactors. A combination of low temperature photoluminescence spectroscopy, X-Ray diffractometry, and transmission electron microscopy attest the quality of the new material. We end with a suggestion for the next steps to exceed technological readiness levels of 8, and use monolithic RTD emitters as components in new systems.

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Section: Introductionmentioning

confidence: 99%

Resonant Tunnelling Diodes for next generation THz systems

Baba

Jacobs

Stevens

et al. 2018

2018 IEEE British and Irish Conference on Optics and Photonics (BICOP)

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“…A number of spectroscopic sensing THz systems using different technologies have demonstrated trace gas detection of different components over the last decade or so [2][3][4]. Bigourd et.…”

Section: Introductionmentioning

confidence: 99%

Chirped-pulse terahertz spectroscopy for broadband trace gas sensing

Gerecht¹,

Douglass²,

Plusquellic³

2011

Opt. Express

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We report the first demonstration of a broadband trace gas sensor based on chirp-pulse terahertz spectroscopy. The advent of newly developed solid state sources and sensitive heterodyne detectors for the terahertz frequency range have made it possible to generate and detect precise arbitrary waveforms at THz frequencies with ultra-low phase noise. In order to maximize sensitivity, the sample gas is first polarized using sub-μs chirped THz pulses and the free inductive decays (FIDs) are then detected using a heterodyne receiver. This approach allows for a rapid broadband multi-component sensing with low parts in 10(9) (ppb) sensitivities and spectral frequency accuracy of <20 kHz in real-time. Such a system can be configured into a portable, easy to use, and relatively inexpensive sensing platform.

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“…It is continuous-wave THz spectroscopy (cw-TS) where two near-infrared cw-lasers, with their difference frequency equal to the desired THz frequency, are superimposed and focused onto GaAs or InGaAs photo-mixers producing narrow-band THz radiation [6]. With these technological developments, THz spectroscopy has seen increasing use in various disciplinary areas ranging from analytical chemistry to combustion [7,8]. Furthermore, since most non-polar materials are transparent to THz radiation these sources are suitable for solid-state characterization of material properties such as the complex dielectric function or the moisture content of hygroscopic materials such as plastics or clothes [9].…”

Section: Introductionmentioning

confidence: 99%

Broadband cw-terahertz spectroscopy for characterizing reactive plasmas

Ouaras¹,

Righetti²,

Cappelli³

2019

J. Phys. D: Appl. Phys.

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Terahertz spectroscopy is seeing increasing use in analytical chemistry because of its ability to access ground state molecular rotational and vibrational transitions. Experiments reported on the use of THz spectroscopy to the studies of low pressure plasmas have focused on the use of pulsed sources, which have limited spectral resolution. These are suitable in the characterization of plasma parameters such as electron density, but somewhat inadequate in the study of molecular absorption spectra. The recent commercial availability of continuous THz sources with much higher spectral resolution has afforded the detailed probing of molecular absorption features but they have not yet been exploited in studies of low pressure plasma chemistry. One of the major benefits of continuous-wave THz spectroscopy (cw-TS) compared to optical and infrared methods is its applicability to the study of both plasma chemistry as well as parameters, i.e. electron density and collision frequency. In this article, we provide first insights into the use of cw-TS as a plasma diagnostic, and demonstrate the opportunities and challenges by example measurements in a low-pressure argon-methanol radio frequency inductively coupled plasma in which we estimate both the plasma-induced dissociation in the precursor methanol concentration, as well as the electron density and momentum scattering collision frequency.

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In situ Measurement of Combustion Gas Using Terahertz Time Domain Spectroscopy Setup for Gas Phase Spectroscopy and Measurement of Solid Sample

Cited by 14 publications

References 30 publications

Resonant Tunnelling Diodes for next generation THz systems

Resonant Tunnelling Diodes for next generation THz systems

Chirped-pulse terahertz spectroscopy for broadband trace gas sensing

Broadband cw-terahertz spectroscopy for characterizing reactive plasmas

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