The Brillouin scattering spectrum of a photonic crystal fiber was measured experimentally by core-offset splicing to a
single mode fiber. One main peak and five sub-peaks due to Brillouin scattering were identified and their frequency and
intensity dependences on strain and temperature were investigated in detail. Besides the frequency shift, the intensity of
the Brillouin scattering was also found to vary with strain and temperature changes. It is then expected to solve the
problem of cross sensitivity in the conventional single-mode fibers.
We present a high-sensitivity hydrostatic pressure sensor based on a dual-polarization fiber grating laser. To enhance the
sensitivity, the laser is embedded in a composite structure to effectively convert the pressure into intra-cavity
birefringence. The measurement is carried out by monitoring the beat frequency between the two orthogonal polarization
laser modes. The pressure sensitivity reaches 0.17 GHz/MPa within the range 0 to 10 MPa, about one hundred times
higher than the bare laser, and the minimal detectable pressure change is as small as 10 kPa.