High-Performance In-Line Brillouin Optical Correlation Domain Analysis

We demonstrate a high-performance single-ended correlation-domain Brillouin sensor based on a phase modulation of Brillouin pump and a differential measurement scheme. Large DC noise induced by direct reflection of Brillouin pump was successfully removed by the phase modulation-based differential measurement as well as additional 4-fold enhancement in the spatial resolution. By applying an intentional loss to the end of a sensing fiber one of two correlation peaks within the fiber is suppressed, leading to double enlargement of the measurement range compared to former in-line reflector based systems. In the experimental confirmation a distributed strain measurement with a range of 100 m and a spatial resolution of 5 cm is presented.