Carbon-steel tube surface mounted FBG sensors under high-temperature environment, part II: Gold coated and femtosecond laser written

Fiber Bragg grating (FBG) sensors must be mounted at the outer surface of a metallic test-piece or embedded into a testing surface to be able to perform continuous condition monitoring. Robust mounting and reliable operation of such sensors for parameter monitoring in high-temperature operating environment is still a key challenge. Here, in the second part of the two-part article, we focus on the mounting of gold-coated femtosecond laser written FBG sensors on a carbon-steel tube and performance monitoring of the packaged sensors for temperature up to 500°C, for three consecutive thermal cycles. The sensors experience a remarkable sensitivity to temperature, 28 pm/° C.