Abstract:
A high sensitivity dual-fiber-Bragg-gratings (FBGs) based strain sensing system is proposed. It consists of two FBGs with different center reflection wavelengths (1546.209 nm and 1541.716 nm), which are respectively sticked on the upper surface and lower surface of a triangle cantilever beam of constant bending rigidity. Through measuring the relationship between the two FBG’s center reflection wavelength difference and the strain of the triangle cantilever beam, the strain fiber sensing can be achieved. The simulations have demonstrated that the sensitivity of the dual-FBGs based strain sensing system is two times of that of the single-FBG based one, and the temperature influence can be compensated automatically in the proposed sensing system. The experimental data verify the conclusion draw from the simulations, show a strain sensing sensitivity of 2.10 pm/με, and demonstrate that the measurement accuracy is safe from the temperature variation induced influence.

Key words: fiber Bragg grating, strain sensing system, high sensitivity, dual-fiber-Bragg-gratings