The effect of pressures up to 200 kPa on pi-phase-shifted Bragg gratings was investigated in several types of
fibers placed in a pressure chamber. Standard and alternative types of pi-phase shifted gratings were studied,
and changes in reflection spectra caused by pressure changes were monitored. The alternative pi-phase shifted
grating was fabricated using a phase mask with 536-nm pitch exhibiting features at twice the Bragg
wavelength near 1552 nm due to the interleaved refractive index modulations along the fiber core with the
periodicity of the phase mask. The three gratings studied exhibited quite different variation in Bragg
wavelength with increased pressure for the different fiber types, and the alternative pi-phase-shifted grating in
Corning HI 1060 FLEX fiber also suffered a significant change in the shape of the peaks.