Wavelength stability of sweepmeter-based tunable laser spectrometer

Optical fiber sensors must compete in performance with traditional electronic sensors, such as quartz crystal pressure and temperature monitors. The precision of commercial electronic sensors can reach the parts-per-billion (ppb) level. To test the precision of a laser based spectrometer system, repeated measurements of an absorption line of a molecular gas cell were made. The Allan deviation is computed, and it is shown that the laser interrogation system, built completely out of commercially available components, can achieve precision at the 10-ppb level.