FBG Accelerometer With High Figure of Merit Based on Double Short Gratings

The tradeoff between sensitivity and frequency band is problematic for fiber Bragg grating (FBG) accelerometer, and synchronous enhancement is an urgent technical problem. We report a novel fiber-optic accelerometer with high figure of merit (FOM) based on double short gratings, which are inscribed by a femtosecond laser and symmetrically fixed to an M-shaped hinge to increase the sensitivity and reduce the temperature interference. Experiments show that the sensor possesses a resonant frequency of 400 Hz, a high acceleration sensitivity of 729.24 pm/g (1.5 dB), and a high FOM of 116 678 400 pm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>g<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}} \cdot $ </tex-math></inline-formula>Hz2, which is higher than the level (5 000 000 pm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>g<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}} \cdot $ </tex-math></inline-formula>Hz2) of conventional FBG sensors. The sensor has great potential in low-frequency (as low as 0.1 Hz) microvibration measurement.