Operation of Brillouin Optical Correlation-Domain Reflectometry: Theoretical Analysis and Experimental Validation

We theoretically and experimentally analyze the operation of Brillouin optical correlation-domain reflectometry (BOCDR). First, we experimentally confirm that BOCDR is not based on stimulated Brillouin scattering but on spontaneous Brillouin scattering. Then, we theoretically prove that the spatial resolution of BOCDR is given well by the same expression as that of Brillouin optical correlation-domain analysis (BOCDA). Finally, we demonstrate that the modulation amplitude of the laser frequency, which has been conventionally limited to a half of the Brillouin frequency shift, can be enhanced further by employing a sensing fiber shorter than a half of the measurement range.