Noise level estimation of BOTDA for optimal non-local means denoising.

Due to the similarity of Brillouin optical time domain analyzer (BOTDA) signals, image denoising could be utilized to remove the noise. However, the performance can be much degraded due to inaccurate noise level estimation. By numerical and experimental study, we compare the noise level estimation of three different methods for BOTDA: calculating the standard deviation (STD) of the measurements, a filter-based estimation algorithm, and a patch-based estimation algorithm proposed in this paper, which selects weak textured patches of BOTDA signal and then estimates noise level using principal component analysis (W-PCA).

Long-distance random fiber laser point sensing system incorporating active fiber.

In this paper, we investigate the benefits of introducing the active fiber into long-distance point-sensing system based on random fiber laser (RFL). In this scheme the active fiber is placed between two segments of single mode fiber (SMF) and backward RFL pumping scheme is used. Through the numerical analysis, the influence of active fiber location on the spectral and power performance for the RFL is carefully discussed.

Coherent Φ-OTDR based on I/Q demodulation and homodyne detection.

We demonstrate a novel distributed acoustic sensing (DAS) system based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). Both the phase and the amplitude of the Rayleigh scattering (RS) light can be demodulated in real-time. The technique is based on I/Q demodulation and homodyne detection using a 90° optical hybrid.