Gas-Flow Sensor using Optical Fiber Bragg Grating(FBG)

We have proposed and demonstrated an gas-flow sensor using optical fiber bragg grating(FBG) The flow sensor Ins no electronics and no mechanical parts in its sensing part and the structure is thus simple and immune to electromagnetic interference(EMU). The FBG sensor was consisted of the sensing element and a coil heater. The metal coil was used to supply the current to the FBG. While some currents supply to the coil, the refractive index of the FBG under the coil is changed and thus the wavelength shift of fiber optic sensor was induced In this work, the wavelength shift according to flow - rate was experimentally studied and was used to evaluate the gas flow- rate in a gas tube. As a result, it was possible to measure the flow - rate in a linear range from 5 to 20ℓ )/ min with a resolution of approximately 1ℓ ) /min at the applied currents of 100 mA and 120 mA The measured sensitivities were 15.3 pm/ ℓ / min for 100 mA and 20.2 pm/ℓ / min for 120 mA.