CAVITY ENHANCED ABSORPTION SPECTROSCOPY IN THE $0.8\mu$m REGION

Abstract

Since the pioneering work by $O'Keefe and Deacon,^{a}$ cavity ring down spectroscopy has been widely recognized as a sensitive technique for absorption spectroscopy. A variation of the technique, cavity enhanced absorption spectroscopy (CEAS) combined with phase sensitive detection initiated by Peeters $et al.^{b}$ has been adopted in our laboratory using our newly built high resolution Ti:sapphire laser spectrometer and a 1.5 meter cavity ring down cell sealed with high reflection $(>99.97%)$ concave mirrors. Comparing to the typical CEAS using a fast digital oscilloscope, this implementation improves the signal-to-noise ratio by a factor of 2-3 for the transitions of acetylene in the $0.8\mu$m region. In this paper, the experimental setup and the performance of our system will be discussed.