Temperature-insensitive multipoint strain-sensing system based on fiber Bragg gratings and optical power detection scheme

This work presents a new temperature-insensitive multipoint strain sensor based on fiber Bragg gratings. A divider circuit at the post detection port compensates for optical power variation and thermal instability induced by the nonflatness of the source spectrum. Experimental results show a measurement resolution of ±0.35 μS and a temperature stability of ±0.005% for no strain (±0.48% for a strain of <400 μS) in an example with two sensing points. A measurement linearity of ±0.17% is estimated in the range 0 to 350 μS with no crosstalk.