We present, to our knowledge for the first time, a 100-km Brillouin Optical Frequency-Domain Analysis (BOFDA) employing a 200-km fiber loop. Compared to our previous publication, enhanced sensor length, sensor accuracy and spatial resolution are presented. The performance improvements are achieved by applying distributed Raman amplification (DRA) and a digital high-pass filter. We report on temperature measurements over sensing distances of 75 km and 100 km both with a 12.5-m spatial resolution. Temperature changes of 5 ° C have been measured along 75 km sensing fiber. A temperature change of 30 ° C has been detected at 99.5 km.
Keywords: BOFDA; distributed Brillouin sensing; distributed temperature and strain sensing; fiber optics sensors; stimulated Brillouin scattering.