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C. ISHIBASHI, M. L. SILVA, J. YE AND J. L. HALL, JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440.
Cavity-enhanced spectroscopy is a useful technique to achieve high sensitivity, which realizes observation of week absorption such as molecular vibrational overtone bands . Comparing to cavity-ringdown spectroscopy, cavity-enhanced spectroscopy using CW laser is more suitable for laser frequency stabilization or high resolution spectroscopy. High signal to noise ration obtained by cavity-enhanced spectroscopy helps to realize ultra-high stability of laser frequency with a tabletop-compact spectrometer. The expected stability of laser frequency was analyzed and spectrometer was built for Nd:YAG laser stabilized to a hyperfine resolved X-B band transition of iodine at 532 nm. The combination technique of frequency modulation spectroscopy and cavity enhanced spectroscopy called NICE-OHMS (noise immune cavity- enhanced optical heterodyne molecular spectroscopy) makes it easy to achieve shot-noise limited detection with an extremely high finesse cavity. NICE-OHMS is being prepared to hyperfine resolved high resolution spectroscopy of v = 0-5 band of HBr at 790 nm region.