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Monolithic Folded Resonator for Evanescent Wave Cavity Ringdown Spectroscopy
Published
Author(s)
A C. Pipino
Abstract
An optical resonator is characterized that employs both ultra-high-reflective coated surfaces and total-internal reflection to enable cavity ring-down spectroscopy of surfaces, films, and liquids. The monolithic design possesses a polarization-independent finesse which allows polarization-dependent phenomena, such as molecular orientation, to be probed. Although a restricted bandwidth ({approximately equal to} 80 nm) results from the use of optical coatings, the resonator provides high-sensitivity, excellent stability, and facile operation for narrow bandwidth applications. A noise equivalent absorption of 6.4 x 10-7 Hz-1/2 was obtained using multimode excitation at 530 nm. Improvements in sensitivity of 10 to 104 appear feasible, depending on the spectral region.