Multi-wavelength tunable lasers for gas spectroscopy

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In process industry, environmental and medical applications, it can be important to measure the concentration of many gas species simultaneously and rapidly, to give real-time information. Examples include; - Measurement of combustion feedstocks and effluent gases, important in the drive for reduced carbon emissions. - Detection of hydrocarbons and hydrogen sulfide in the natural gas industry and biogas generation industries - Detection of toxic species in industry, such as ammonia and hydrogen fluoride - Breath gas diagnostics, to diagnose and anage diseases such as asthma, diabetes, renal disease, cystic fibrosis and others. - Measuring short-lived gas species, to improve urban air quality and understand important atmospheric processes affecting climate change. These activities present a significant measurement problem to industrial users. Industrial gas detection is dominated by complex and expensive laboratory equipment with sampling that precludes real-time measurement and can even affect the composition of the sample through condensation and / or reaction in the sample pipework. Small ultra-low-cost devices are also available, however these do not offer the stability nor the gas species specificity needed for industrial applications. Many gases of interest absorb light at specific and characteristic wavelengths in the near infrared region of the spectrum (1.3 - 2.5 microns). Using a suitable laser source whose emission is at known and controlled wavelengths, this property forms the basis of a powerful method to detect gases and measure their concentrations.Our new approach to optical gas detection, based on development of a new class of optical sources, will enable both multi-species detection as well as detection of unstable species, both of which are difficult to impossible with existing technology. Demonstration of these sources will initially include detection of hydrocarbons, carbon dioxide and carbon monoxide, then lead on to measurement of unstable species such as hydrogen sulfide and ammonia..