Distributed Fiber Birefringence Measurement Using Pulse-Compression Φ-OTDR

Abstract

In this paper, a novel birefringence measurement method through the Rayleigh backscattered lightwave within single-mode fiber is proposed, using a single chirped-pulse with arbitrary state of polarization. Numerical analysis is carried out in detail, then pulse-compression phase-sensitive optical time domain reflectometry (PC-Φ-OTDR) with polarization-diverse coherent detection is employed to verify this method. A 2km spun single-mode fiber is tested with 8.6 cm spatial resolution, and the average birefringence of the fiber under test is measured as 0.234rad/m, which is consistent with previous literatures about single-mode fiber. Moreover, the relationship between the measured birefringence and the spatial resolution is also studied for the first time, and the results show that spatial resolution is crucial for fiber birefringence measurement.

Research Progress in Distributed Acoustic Sensing Techniques

“…The spatial resolution was determined by the bandwidth and mismatch ratio of the chirped pulses rather than the pulse duration, so the spatial resolution could be adjusted to suit the actual requirements by varying the mismatch ratio. The system was available with a spatial resolution of up to 2 m. In 2021, Wang et al proposed a new method for birefringence measurement using the RBS wave in a single-mode optical fiber [51] (Figure 11). The experiment showed a spatial resolution of 8.6 cm and an average birefringence of To determine the relationship between spatial resolution and SNR, in 2019, Zhang et al proposed a sensing scheme with multiple spatial resolutions (MSRs) for analyzing Φ-OTDR sensing systems.…”

Recent Advances in Phase-Sensitive Optical Time Domain Reflectometry (Ф-OTDR)

“…After that, the experiment was conducted and successfully demodulated the birefringence information in a 2 km spun SSMF with 8.6 cm spatial resolution (as shown in Fig. 15), which could play a significant role in high-sensitivity bending, stressing, and twisting sensing [42]. However, 90° optical hybrid has some inherent imperfections, which will cause distortions in demodulated sensing signal [43].…”

A Concise and Adaptive Sidelobe Suppression Algorithm Based on LMS Filter for Pulse-Compressed Signal of Φ-OTDR

“…In order to meet these challenges, an effective method using the pulse compression technique to realize the modulation and demodulation of probe pulses is proposed [6][7][8]. Pulse compression technique is a commonly used radar detection enhancement technique, which is used to interconvert broadband signals into narrowband signals, and can change the time width and frequency bandwidth of the signal without changing the signal energy.…”