Double-Slope Assisted Brillouin Optical Time Domain Reflectometry With Linear Regions Merging

A novel and fast double-slope assisted Brillouin optical time domain reflectometry (DSA-BOTDR) with linear regions merging has been proposed to enlarge the measurement range. In the proposed method, the linear regions of the left and right slopes of the Brillouin gain spectrum (BGS) are both used, and the positions of the two linear regions can be controlled by setting a suitable bandwidth of band-pass filter in acquisition system. Thus the linear regions can be merged together and the measurement range can be enlarged greatly. In a proof-of-concept experiment, a frequency measurement range of about 190 MHz is obtained in DSA-BOTDR, which is about 3.8 times of the conventional slope-assisted BOTDR (SA-BOTDR). In addition, the temperature of an 800 m polyimide coated fiber is measured within 0.4 s with 3 m spatial resolution. Moreover, a measurement range of 100.3 °C with a temperature uncertainty of 1.0 °C is successfully proved.