For the efficient operation of a cavity ringdown spectroscopy (CRDS) system utilized with a continuous-wave (cw) laser, we numerically analyze the coupling efficiency of a cw laser to a ringdown cavity in terms of changes in the scanning rate, the laser linewidth, and the mirror reflectivity. We also demonstrate a new simple design for a CRDS system that can produce a CRDS signal with only a piezoelectric transducer (PZT), without the acousto-optic modulator that is usually adopted to switch off the cw laser beam that enters the cavity. Furthermore, we investigate the feasibility of the cw CRDS technique with a fast-scanning PZT by recording a CRDS spectrum of acetylene overtones. The detection sensitivity that corresponds to the noise-equivalent absorption is found to be ~3 × 10<sup>−9</sup>/cm.
© 1999 Optical Society of America
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
(300.0300) Spectroscopy : Spectroscopy
(300.6360) Spectroscopy : Spectroscopy, laser
Jae Won Hahn, Yong Shim Yoo, Jae Yong Lee, Jae Wan Kim, and Hai-Woong Lee, "Cavity RingDown Spectroscopy with a Continuous-wave Laser: Calculation of Coupling Efficiency and a New Spectrometer Design," Appl. Opt. 38, 1859-1866 (1999)