Fiber Bragg grating pair interferometer sensor with enhanced multiplexing capacity

A new technique monitoring and multiplexing FBG pair interferometer sensors with linear chirped fiber laser is investigated. It demonstrates the enhanced multiplexing capacity over a conventional WDM FBG sensor system by allowing multiple sensors to share the same optical bandwidth. It is concluded that the sensing elements are low-finesse Fabry-Perot interferometers formed using Bragg grating mirrors with similar spectral characteristics. Multiplexing of two interferometers of different lengths with a linear chirped erbium-doped fiber laser has been demonstrated. Their signals are distinguished through convolution with appropriately matched reference waveforms, even though the reflectance spectra for the FBGs for the two sensors overlap over a wide temperature range.