Formation of Fiber Tapers by Chemical Etching for Application in Chaotic Correlation Fiber Loop Ring Down Sensing

Fiber loop ring down spectroscopy has been developed into a high-sensitivity technique for sensing many important characteristics of samples, such as refractive index. In contrast to the previous demonstrations by using mode-locked fiber laser, this work is demonstrated to use chaotic laser combined with fiber loop ring down sensor. The formation and performance of fiber tapers was monitored by combining chaotic fiber ring down technology on line and in real time. Two sets of refractive index sensing experiments are performed and further analyzed by using the proposed setup. The results are shown that the detection limit of the chaotic correlation fiber loop ring down system is 3.45 × 10−4 RIU and the sensitivity is 0.0682 ns−1RIU−1 in 6.7 m, respectively. The performance of our system can be drastically improved by increasing the length of the etched fiber tapers to be tens of centimeters using the chaotic correlation fiber loop ring down system with the smaller fiber ring lengths.