A loss-compensated fiber loop available for short-pulse lasers and its application in water detection

Abstract

The concentration of trace sample can be determined by, and therefore an indicator of, the absorption property in fiberloop ring-down spectroscopy. The aim of this study was to investigate the use of an ultrashort-pulse laser as a source of the fiber-loop ring-down spectroscopy and its applicability for loss-compensated fiber loops. A composite-type carbonnanotube saturable absorber mode-locked fiber laser was built to be used as a source of experimental setup. The simulation has been done to check dispersion effects on ring-down signals, and it was found that the initial pulse duration affected ring-down information. To avoid this limitation, we just used the chirped pulses without any compensation process in the experiment. A loss-compensated fiber loop was constructed to measure the concentration of water in water/acetone mixture samples. The measurements were shown to lead to an accurate determination of the ringdown time. The result indicates that it is possible to measure the sample-induced absorption with the ultrashort-pulse laser source and loss-compensated fiber loop to determine the concentration of the sample.