Development of Optical Sources for Gas Sensing Applications

基于激光的吸收光谱可以在许多工业应用中用于测量过程控制，燃烧诊断，环境监测和排放测量的物质浓度，并且可以以各种形式应用（波长调制光谱- WMS，腔衰落光谱- CRDS，光声光谱- PAS）。EEE部门微系统和光电子中心内的应用高分辨率光谱中心（CAHRS）与大量工业和学术合作伙伴（包括劳斯莱斯，西门子，LG燃料电池，Optosci Ltd， M Squared激光器）在实施这些技术方面拥有超过20年的经验。本研究的目的是研究各种光源和新的光学传感技术，以测量目标物种（CO， CO2和H2O）的光谱参数。这将包括使用快速调谐速率量子级联激光器的研究，以了解高温环境中激发分子的弛豫速率，以及围绕2000 nm区域的广泛可调谐源开发，以研究水蒸气和二氧化碳的压力加宽效应。从本质上讲，该项目将支持开发用于航空燃气涡轮发动机（GTE）的破坏性化学物质测量方法，并将其更广泛地应用于其他燃烧排放。学生将首先了解在高温和高压下高精度测量光谱参数的复杂性。然后，他们将对理论吸收光谱进行建模，以确定目标气体的哪些光谱特征适合在燃烧器中进行测量。然后将对所选光谱进行实验测量，以确保其适用性，并测量其展宽参数的温度依赖性。

Laser-based absorption spectroscopy can be utilised in numerous industrial applications to measure species concentrations for process control, combustion diagnostics, environmental monitoring, and emissions measurement, and can be applied in various forms (wavelength modulation spectroscopy - WMS, cavity ringdown spectroscopy - CRDS, photo-acoustic spectroscopy - PAS). The Centre for Applied High Resolution Spectroscopy (CAHRS), within the Centre for Microsystems and Photonics in the EEE department has over 20 years of experience implementing these techniques with a large number of industrial and academic partners, including Rolls-Royce, Siemens, LG Fuel Cells, Optosci Ltd, M Squared Lasers. The aim of this studentship is to investigate various optical sources, and novel optical sensing techniques, for the measurement of the spectral parameters of target species (CO, CO2 and H2O). This will include the investigation of using fast tuning rate quantum cascade lasers, to understand the relaxation rates of excited molecules in high temperature environments, and broadly tunable source development around the 2000 nm region to investigate the pressure broadening effects of water vapour and carbon dioxide. In essence, the project will support the development of a disruptive chemical species measurement method for aero gas turbine engines (GTE) as well as the wider application to other combustion emissions. The student will begin by understanding the complexities of high accuracy measurements of spectroscopic parameters at high temperature and pressure. They will then model theoretical absorption spectra to ascertain which spectral features of the target gases are suitable for measurement in a combustor. The chosen spectra will then be measured experimentally to ensure suitability, and to measure the temperature dependence of their broadening parameters.