An intensity-modulated, fiber Bragg grating (FBG) vibration sensor is proposed and experimentally demonstrated. The
sensing mechanism is based on the measurement of optical power of a strain-chirped FBG. An initially-uniform FBG is
glued with a slanted direction onto the lateral surface of a simply-supported beam (SSB). A mass is fixed in the middle
of the beam, which can transfer the vertical vibration to the deflection of the beam. Therefore, deflection induced
nouniform strain is applied along the sensing FBG and makes it chirped. The reflected optical power from the FBG is
measured with a photodetector (PD) and an oscilloscope. The experimental results are compared with the measurement
results of a resistance strain sensor, and good agreement is achieved. Furthermore, this sensor is cost-effective and
inherently insensitive to temperature.
A novel fiber optic accelerometer is proposed and demonstrated. The sensing mechanism is based on the measurement of
bandwidth and optical power of a strain-chirped fiber Bragg grating (FBG). An initially-uniform FBG is glued with a
slanted direction onto the lateral surface of a simply-supported beam. Two masses are fixed on the top and bottom
surfaces in the middle of the beam respectively, which can transfer the vertical acceleration to the deflection of the beam.
Therefore, deflection induced nouniform strain is applied along the sensing FBG and makes it chirped. Experimental
results show that 3-dB bandwidth and reflected optical power of the strain-chirped FBG responds to acceleration
sensitively. The achieved sensitivities are up to 0.4 nm/g and 4.57 μW/g respectively in the linear range. Furthermore,
this sensor is very cost-effective and inherently insensitive to temperature due to the simple demodulation method.
An acceleration sensor based on measurement of the reflection bandwidth of a single fiber Bragg grating (FBG) is
presented. The FBG is glued in a slanted direction onto the lateral surface at the center of the beam. Two weights were
fixed respectively on the upper and lower surfaces in the middle of the beam to sense the variation of the acceleration in
the vertical direction. Preliminary experimental results indicate that when the acceleration was increased, the 3-dB
bandwidth of the FBG responded linearly from zero to 8 g, with very low temperature dependence. The measurement
sensitivity and resolution are 0.4 nm/g and 0.05 g, respectively.
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