Abstract
Two optical fiber Bragg gratings (FBGs) of slightly separated Bragg wavelengths were tandem spliced for temperature-insensitive strain sensing. The two 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 system, which was determined by the union of the spectra of the two FBGs. Linear strain measurement up to 740 μS with strain accuracy of ±1.1 μs and thermal stability of <0.7% in detected power in the temperature range from 19 to 103 °C was obtained. © 2001 Elsevier Science B.V. All rights reserved.