Novel Brillouin Optical Time-Domain Analyzer for Extreme Sensing Range Using High-Power Flat Frequency-Coded Pump Pulses

In this paper, we propose a novel Brillouin optical time-domain analysis setup that combines simultaneous Brillouin gain/loss measurements with colour coding. This technique gives the advantage that the pump power can greatly be increased, compared to other coding schemes; thus, increasing the sensing range. A first measurement over a 200-km fiber loop is performed, with a 3-m spatial resolution and an accuracy of +/- 3 MHz (2s) at the end of the sensing fiber. In a second setup, high-power flat pump pulses are generated by applying an arbitrary waveform signal on a frequency shifter; thus, further increasing the performance of the novel Brillouin sensor. To the best of our knowledge, these are the best results obtained with a Brillouin sensor without Raman amplification.