Compact Anemometer Using Silver-Coated Fiber Bragg Grating

An optical fiber thermal anemometer is proposed based on a silver film-coated fiber Bragg grating (FBG) assisted by a core offset fusion splice. Light from a pump laser propagating along the fiber is coupled into the fiber cladding by the splice and absorbed by the silver film to generate heat and increase the temperature of the FBG. Air flow cools down the FBG and its velocity can be measured by the Bragg wavelength shift of the FBG. Experimental results show that the proposed FBG thermal anemometer allows a high resolution of 0.022 m/s in a range up to 6 m/s.