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Coupled-cavity ring-down spectroscopy technique



Jeremie B. Courtois, Joseph T. Hodges


We present a technique called coupled-cavity ring-down spectroscopy (CC-RDS) for controlling the finesse of an optical resonator. Applications include extending the sensitivity and dynamic range of a cavity-enhanced spectrometer, as well as widening the useful spectral region of high-reflectivity mirrors. CC-RDS uses controlled feedback of the probe laser beam to a length-stabilized ring-down cavity, which leads to interference between the internally circulating light and that which is fed back through the cavity input mirror. Using a feedback cavity with a finesse of 16, we demonstrate that this effect increases the ring-down cavity time constant from 210 µs to 280 µs, corresponding to an increase of finesse from 2.7105 to 3.6105. Finally, we show that with the addition of a second feedback cavity, we observe ring-down times as long as 0.50 ms, equivalent to a finesse of 6.4105 and an effective mirror transmittance of 4.9106.
Optics Letters


cavity ring-down spectroscopy, etalons, coupled-cavities, finesse


Courtois, J. and Hodges, J. (2012), Coupled-cavity ring-down spectroscopy technique, Optics Letters, [online], (Accessed June 19, 2024)


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Created August 5, 2012, Updated October 12, 2021