Cavity-enhanced absorption spectroscopy with continuous and fast wavelength tuning

We report the development of cavity-enhanced laser absorption spectroscopy with continuous wavelength tuning using a dual-feedback locking scheme.A compact optical cavity of 8 cm is used for achieving an effective optical path of 80 m in a volume of only 10 mL.Compared to the traditional cavity-enhanced absorption spectrometers, our approach sweeps an absorption feature with a full width at half-maximum (FWHM) of 420 MHz in 5 s, achieving a spectral resolution at the MHz level.We also introduce, to our knowledge, a novel method to easily and precisely calibrate the frequency tuning range.Our study proves the feasibility of conducting high-sensitivity, high-resolution, and rapidly tunable absorption spectroscopy in an optical cavity.