Cavity ring-down spectroscopy with a laser frequency stabilized and locked to a reference target gas absorption for drift-free accurate gas sensing measurements

Trace Gas Detection with Cw Cavity Ring-down Laser Absorption Spectroscopy

Cavity-locked ring-down spectroscopy

Pound-Drever-Hall-locked, frequency-stabilized cavity ring-down spectrometer.

We describe a high sensitivity and high spectral resolution laser absorption spectrometer based upon the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique. We used the Pound-Drever-Hall (PDH) method to lock the probe laser to the high-finesse ring-down cavity. We show that the concomitant narrowing of the probe laser line width leads to dramatically increased ring-down even...

Cavity ring-down spectroscopy for quantitative absorption measurements

We examine under what conditions cavity ring-down spectroscopy ~CRDS! can be used for quantitative diagnostics of molecular species. We show that CRDS is appropriate for diagnostics of species whose absorption features are wider than the spacing between longitudinal modes of the optical cavity. For these species, the absorption coefficient can be measured by CRDS without a knowledge of the puls...

Repetitively Mode-Locked Cavity-Enhanced Absorption Spectroscopy (RML-CEAS) for Near-Infrared Gas Sensing

A Pound-Drever-Hall (PDH)-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT) and proportional-integral-derivative (PID) feedback control of diode laser current were used to repetitively lock the laser modes to the cav...