Temperature-insensitive linear strain measurement using two fiber Bragg gratings in a power detection scheme

Two optical fiber Bragg gratings (FBGs) of slightly separated Bragg wavelen gths were tandem spliced for temperature-insensitive strain sensing. The tw o FBGs, one used for sensing and the other used for reference, were placed side by side in parallel to assure that they had the same thermal condition . Strain was calibrated simply through reflected power measurement of the s ystem, which was determined by the union of the spectra of the two FBGs. Li near strain measurement up to 740 muS with strain accuracy of +/-1.1 mus an d thermal stability of <0.7% in detected power in the temperature range fro m 19 to 103 <degrees>C was obtained. (C) 2001 Elsevier Science B.V. All rig hts reserved.