Pressure and temperature cross sensing restricted the application of bare fiber FBG , especially when FBG was
used to measure low hydrostatic pressure. Side-hole package is practical to overcome pressure and temperature
cross sensing and enhance FBG pressure sensitivity to measure hydrostatic pressure, but it aroused package
stability problem that the FBG spectrum seemed distortion, which will brought measurement difficulties. Novel
side-hole package was raised, with reasonable structure and mechanism, to improve the package stability and
eliminate FBG distortion. The theoretical analysis presented the stress and deformation in fiber core within
packages, and forecast the birefringence may be amplified in novel package according to the package structure,
which will support the measurement based on polarization spectrum technique. The experiment result proved
theoretical analysis and shown that the novel side-hole package provided stability support while kept the
advantage of the former side-hole package.
The finite element method was used to analyze the interior stress distributions and the birefringence of the side hole fiber. The paper has analyzed the dependence of the birefringence of the side hole fiber on the side holes' physical dimensions. The calculation result shows that the fast axis of the fiber is along the line which links the two holes' centers, the geometrical birefringence can be neglected, and the birefringence can be improved through increasing the radius of the side holes or reducing the distance between the core and the side hole centers.