Fiber Bragg grating sensing multiplexing system based on interferometric demodulation technique

Controlled by an optical switch, fiber Bragg grating sensing system based on spatial division multiplexing was achieved when a broad-band source illumines FBG sensor array. With an isosceles triangle cantilever beam to realize linear tuning of Bragg wavelength of fiber grating without chirping by adjusting the deflection of the free end, the system employs an unbalanced Mach-Zehnder interferometer to translate the FBG wavelength signal related the strain into phase signal. The strain can be recovered by measuring the phase change of the signal with signal processing circuit. With the characteristic of high resolution and wide measurement range, this sensing system has the capability of measuring static strain as well as dynamic strain. Experiment demonstrated that the sensing sensitivity was 0.82°/με.