Determination of the K-matrix for the multiparameter fiber grating sensor in AD072 fibercore fiber

A methodology is described for determining a relation (K- matrix) between wavelength shifts and (1) axial strain, (2) two transverse strains and (3) temperature change experienced by a multi-parameter Bragg grating sensor. The sensor is formed by writing gratings at two wavelengths in polarization maintaining fiber. The methodology is based on separate experimental calibrations of sensor response to transverse loading (diametral compression), axial loading and temperature changes. Strains produced in the core by the loadings or temperature changes used in the calibrations are determined by finite element analyses.