Quantum-noise-limited cavity ring-down spectroscopy

• DOI: 10.1007/s00340-014-5808-z
• Publication Date: 2014-03-28T17:20:29Z
• Authors: D. A. Long; A. J. Fleisher; S. Wójtewicz; J. T. Hodges
• Keywords: Cavity Ring-Down Spectroscopy; Heterodyne (poetry); Quantum limit

We demonstrate a heterodyne-detected cavity ring-down spectroscopy (CRDS) method that allows for a noise-equivalent absorption coefficient of 6 × 10−14 cm−1 Hz−1/2, the lowest which has been reported in a CRDS measurement. It is shown that heterodyne-detected CRDS also reaches the quantum noise limit at reasonable optical powers. In addition to offering ultra-high sensitivity, this technique provides high frequency agility over a range of 2 THz in the near-infrared, which allows entire absorption bands to be recorded in minutes. As a demonstration experiment, high resolution spectra of a near-infrared carbon dioxide band have been recorded.