A new modality for the detection of chemical vapors using middle infrared femtosecond pulse propagation e ects

摘要

We have shown recently that unique optical signatures can be observed with the measurement of ultrashortmiddle infrared laser pulses that have been transmitted through molecular vapors. Here, we report on anincreased signal-to-noise ratio of the pulse measurements by using a cross-correlation technique with a lockinamplifier. Carbon tetrauoride and dimethyl methylphosphonate (DMMP) cross-correlation signatures arehighly discriminated using principal component analysis. A squared exponential Gaussian process regressionmodel is used to quantitatively predict the concentration of DMMP.