We propose and experimentally demonstrate the feasibility of a highly efficient FBG-based quasi-distributed sensing system employing dual-wavelength cyclic pulse coding. Significant improvement in the measurement range, resolution and TDM multiplexing capabilities can be achieved, as well as crosstalk reduction with respect to a single wavelength TDM-based FBG interrogation scheme. The mechanism of noise reduction by quasi-periodic cyclic coding is experimentally demonstrated, pointing out significant improvement in accuracy with respect to dual-wavelength single pulse TDM-based FBG interrogation. The proposed technique can also enhance the sensing range of hybrid fiber optic sensor systems in which continuous monitoring of distributed and discrete points are simultaneously measured over the same sensing fiber.
We propose and experimentally demonstrate for the first time to the best of our knowledge the feasibility of an integrated hybrid optical fiber sensing system that efficiently combines distributed Brillouin optical frequency-domain analysis (BOFDA) technique with FBG-based quasi-distributed approach offering the possibility for simultaneous distributed and point-wise measurements. The highly integrated proposed scheme employs Gaussian shaped, broadband and low reflectivity apodized FBGs with a common narrow-band optical source and shared receiving unit over the same sensing fiber. A single mode optical fiber is used for distributed sensing and a pair of FBGs is employed for simultaneous pointwise measurements.
We propose and experimentally demonstrate a hybrid fiber optic sensing technique that effectively combines Brillouin
optical time-domain analysis and a time-domain multiplexing interrogation technique for Fiber Bragg Gratings (FBGs).
The highly-integrated proposed scheme employs broadband apodized low-reflectivity FBGs with a single optical source
and a shared receiver block, allowing for simultaneous measurements of distributed static and discrete dynamic
temperature and strain, over the same sensing fiber.