Incoherent Brillouin Optical Time-Domain Reflectometry With Random State Correlated Brillouin Spectrum

An incoherent Brillouin optical time-domain reflectometry with random state correlated Brillouin spectrum is proposed and experimentally demonstrated for the first time, which is based on a newly developed broadband random light source (chaotic laser) with a bandwidth of four times of the Brillouin spectral width in fiber. A variable optical delay line is introduced to provide location distribution of the temperature or strain in the fiber to replace the optical pulse generator. By adjusting the reference light path, the correlation of the same random state of the Stokes light and the pump light will be measured in the form of the Brillouin spectrum. The spatial resolution is inversely proportional to the bandwidth of the chaotic laser, and hence, the pump wave and Stokes wave are correlated to each other by their identical random state. The experimental result shows a 0.96-m spatial resolution (limited by the bandwidth of the chaotic laser) over a 155-m sensing range.