Coherent BOTDA Sensor With Single-Sideband Modulated Probe Light

In order to optimize the coherent Brillouin optical time domain analysis (BOTDA) sensor for more effective chromatic dispersion (CD) suppression, single-sideband intensity-modulated probe (IMP) light is utilized. Obvious Brillouin gain spectrum distortion due to CD observed in the double-sideband IMP case is successfully cancelled. Meanwhile, frequency preshift for local light generation in other coherent BOTDA sensors that have been reported recently can be avoided in our scheme, resulting in a reduction in system complexity. On the other hand, a logarithmic detector, instead of an inphase/quadrature demodulator, is applied to reduce half of the measurement time. A ~2-m spatial resolution and 0.97 °C temperature accuracy at the end of a 40-km sensing fiber are realized by using a 100-ns/80-ns differential pulsewidth pair.