Abstract: Using hDVS techniques to detect a disturbance in a coherent Rayleigh backscatter caused by the presence of another optical signal in the fiber. The interaction can be caused by a pump pulse travelling shortly after a probe pulse and at a frequency close to that of the probe plus or minus a Brillouin frequency shift. This results in gain or attenuation of the backscatter signal. The Brillouin shift is a function of temperature and strain.

Abstract: Using hDVS techniques to detect a disturbance in a coherent Rayleigh backscatter caused by the presence of another optical signal in the fiber. The interaction can be caused by a pump pulse travelling shortly after a probe pulse and at a frequency close to that of the probe plus or minus a Brillouin frequency shift. This results in gain or attenuation of the backscatter signal. The Brillouin shift is a function of temperature and strain.

Abstract: A fiber optic sensing system includes a fiber optic sensor having a plurality of densely spaced, non-naturally occurring discrete reflectors having a weak reflectivity of less than 1% and, in some cases, even less than 0.0001% depending on the density of the reflectors. The fiber optic sensor is configured so that the spatial resolution of the backscattered signal generated in response to a probe signal is greater than the separation between at least two discrete reflectors, so that backscatter generated by the at least two reflectors overlaps at the receiver. Data representative of a parameter of interest, such as temperature or strain, can be acquired from the detected backscatter and processed in order to provide information about conditions in a region of interest.