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Doppler-broadened mid-infrared NICE-OHMS system based on an optical parametric oscillator
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Physics.
2016 (English)In: Laser Applications to Chemical, Security and Environmental Analysis, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

An OPO-based NICE-OHMS instrument for trace gas detection addressing fundamental vibration transitions in the mid-IR (3.2-3.9 µm) range has been developed. It shows a detection sensitivity for CH4 of 2.4×10−10cm−1Hz−1∕2 (corresponding to low ppt concentrations).

Place, publisher, year, edition, pages
2016.
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:umu:diva-153067DOI: 10.1364/LACSEA.2016.LT2G.2ISBN: 978-1-943580-15-6 (electronic)OAI: oai:DiVA.org:umu-153067DiVA, id: diva2:1261021
Conference
Imaging and Applied Optics 2016, 25–28 July 2016, Heidelberg, Germany
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
In thesis
1. Mid- and near-infrared NICE-OHMS: techniques for ultra-sensitive detection of molecules in gas phase
Open this publication in new window or tab >>Mid- and near-infrared NICE-OHMS: techniques for ultra-sensitive detection of molecules in gas phase
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is a technique for ultra-sensitive detection of molecular absorption and dispersion. For highest performance, the technique combines cavity enhancement (CE) with frequency modulation (FM); while the former increases the effective interaction length between the light and the analyte by several orders of magnitudes, the latter removes the in-coupling of 1/f noise and makes the signals background free. The combination of CE and FM also gives the technique an immunity to amplitude noise caused by the jitter of the laser frequency relative to the cavity resonance frequencies. All these properties make the technique suitable for ultra sensitive trace gas detection in the sub-parts-per-trillion (ppt) range. The aim of this thesis is to improve the performance of the NICE-OHMS technique and to increase its range of applications.

The work in this thesis can be divided into three areas:Firstly, a mid-infrared (MIR)-NICE-OHMS instrumentation was developed. In a first realization an unprecedented white-noise equivalent absorption limit for Doppler broadened (Db) detection in the MIR of 3×10-9 cm-1Hz-1/2was demonstrated. This was subsequently improved to 2.4×10-10 cm-1Hz-1/2allowing for detection methane and its two main isotopologues (CH3D and 13CH4) at their natural abundance.Secondly, further development of an existing near-infrared NICE-OHMS system was performed. This resulted in an improved longtime stability and the first shot-noise limited NICE-OHMS system for Db detection with a noise equivalent absorption limit of 2.3×10-14 cm-1detected over 200 s. Thirdly, models and theoretical descriptions of NICE-OHMS signals under strong absorption conditions and from methane under high laser power were developed. It was experimentally verified that the models allow for a more accurate evaluation of NICE-OHMS signals under a wide range of conditions.

Abstract [sv]

Brusimmun kavitetsförstärkt optisk-heterodyndetekterad molekylärspektroskopi (eng.Noise-immune cavity-enhanced optical heterodyne molecular spectrometry, NICE-OHMS) är en teknik för ultrakänslig detektion av molekylär absorption och dispersion. NICE-OHMS-tekniken kombinerar kavitetsförstärkning (eng. CE) med frekvensmodulering (FM); emedan den första väsentligt ökar den effektiva interaktionslängden mellan ljuset och analyten vilket ökar teknikens känslighet, tar den senare bort inkopplingen av 1/f-brus och gör signalerna bakgrundsfria. Kombinationen av CE och FM ger också tekniken en immunitet mot amplitudstörning som orsakas av jitter hos laserljusets frekvens i förhållande till kavitetsresonansfrekvenserna. Alla dessa egenskaper gör tekniken lämplig för ultrakänslig spårgasdetektering i och under ppt (eng. parts-per-trillion) - området. Syftet med denna avhandling är att förbättra prestandan hos NICE-OHMS-tekniken och att öka dess tillämpningspotential.

Avhandlingen kan delas in i tre delar: Inom den första utvecklades en mid-infraröd (MIR)-NICE-OHMS instrumentering. Vid en första realisering påvisades en aldrig tidigare uppnådd vitt-brus-ekvivalent absorptionsgräns för Dopplerbreddad (Db) detektering i MIR området på 3 × 10-9 cm-1Hz-1/2. Detta förbättrades därefter till 2,4 x 10-10 cm-1Hz-1/2, vilket möjliggör detektering av metan och dess två huvudsakliga isotopologer (CH3D och 13CH4) vid deras naturliga förekomst. Inom det andra området utfördes vidareutveckling av ett existerande NICE-OHMS-system verksamt i det när-infraröda (NIR) området. Detta resulterade i en förbättrad långtidsstabilitet och en brus-ekvivalent absorptionsgräns för Db detektion på 2,3 × 10-14 cm-1 mätt över 200 s. Inom den tredje utvecklades modeller och teoretiska beskrivningar av NICE-OHMS under starka absorptionsförhållanden och från metan under hög laserintensitet. Det var experimentellt verifierat att modellerna möjliggör en mer noggrann utvärdering av NICE-OHMS-signalerunder ett stort antal förhållanden.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2018. p. 139
Keywords
spectrometry, NICE-OHMS, trace gas detection, acetylene, methane, isotopologues, near-infrared, mid-infrared, shot-noise, optical parametric oscillator
National Category
Atom and Molecular Physics and Optics
Research subject
Technical Physics
Identifiers
urn:nbn:se:umu:diva-153068 (URN)978-91-7601-977-1 (ISBN)
Public defence
2018-11-30, N450, Naturvetarhuset, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2018-11-09 Created: 2018-11-06 Last updated: 2018-11-13Bibliographically approved

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Hausmaninger, ThomasSilander, IsakAxner, Ove

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