Suppression of Signal Fading With Multi-Wavelength Laser in Polarization OTDR

In this letter, we present a novel and simple method to suppress the signal fading phenomena in polarization optical time-domain reflectometry (POTDR). A combination of polarization multiplexing and multi-directional polarization analyzing is utilized to achieve the goal. A short polarization maintaining fiber is connected to a multi-wavelength laser source to generate polarization multiplexing probe lightwaves. The signals for different probe lightwaves are demultiplexed by a dense wavelength division multiplexer. Then, the three polarizers with different orientations are used to analyze the signals, respectively. The principle of the method is analyzed in detail. Experiments demonstrate the validity of the system to suppress the signal fading. The proposed method can eliminate the location error of event caused by the signal fading and the signal-to-noise ratio is also improved compared with a traditional POTDR.