This chapter discusses the systematic procedures to calibrate a FBG sensor under temperature and strain. The process starts with the inscription of a FBG in the fiber, followed by spectral characterization, transducer prototype development, laboratory optical setup, and the development of transducers for field application. The characterization must be initially performed without applied temperature or strain and then subsequently with their calibrated application.

This section introduces the theory and isolates the necessary FBG parameters to be calculated during the calibration process for temperature and strain. Recalling the basic Bragg equation, the Bragg wavelength shift is a function of the temperature and strain:

(7.1)