CAVITY RINGDOWN SPECTROSCOPY WITH A CW $CO_{2}$-LASER, MICROWAVE-MODULATED SIDEBAND SYSTEM
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Date
1998
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Publisher
Ohio State University
Abstract
This work reports the first observation of a ringdown decay from an empty resonator using a $< 0.5$ MHz linewidth, cw, carbon dioxide laser with $\sim 1$ mW of microwave sidebands separated 8 GHz to 18 GHz from the $CO_{2}$ carrier frequency. The resonator consists of a Fabry-Perot interferometer with two highly reflective mirrors $(R\sim 99.5\%)$ separated by 1.2 m providing an optical pathlength for absorption of 420 m and a theoretical ringdown time of 800 ns. At present, the lack of availability of highly reflective mid-infrared mirrors places an upper limit on the ringdown time. One of the benefits of using an extremely high resolution laser is that a single mode of the cavity can be selectively monitored. Future investigations with the experimental system include saturation spectroscopy of unstable chemical species, such as ozone, for accurate concentration determination.
Description
Author Institution: Department of Chemistry, Princeton University; Optical Technology Division, National Institute of Standards and Technology