Distributed fiber-optic stress-location measurement by arbitrary shaping of optical coherence function

A functional distributed fiber-optic stress-location measurement technique by arbitrary shaping of the optical coherence function has been demonstrated. The technique measures the distribution or location of stress-induced polarization mode coupling in a polarization-maintaining fiber by manipulating the optical coherence function. The location of applied stress is given by optical path difference between the two polarization modes, which is determined by the synthesis of the coherence function. Three types of coherence function-a scanning peak, a scanning low-sidelobe peak, and a standing triangle-have been synthesized experimentally and used for stress locating. When using the coherence function of scanning peak, the coherence peak is slid to scan over the measurement range by a phase modulation to obtain the stress distribution; when using the triangular coherence function, the detection range is set within a linear slope of the triangle so that the stress location is directly converted into the value of the coherence degree.