Interference-Fading-Free $Phi$ -OTDR Based on Differential Phase Shift Pulsing Technology

In order to mitigate the interference fading problem in a phase-demodulated phase-sensitive optical time-domain reflectometer (Φ-OTDR) based on heterodyne coherent detection, a novel scheme based on differential phase shift pulsing technology is proposed in this letter. A 0-π binary phase shift process is applied on the second half of probe pulses trace by trace, and thus interference fading, whic...