Brillouin scattering in optical tapers drawn from Ge-doped and F-doped silica fibers

In this paper, we analyze the Brillouin scattering properties of optical fiber tapers drawn from Ge-doped and F-doped silica fibers. Finite-element-method (FEM) simulations have been carried out to determine the optical and acoustic waveguiding properties of the tapered fibers, and the corresponding acousto-optic overlap integrals. The numerical results are compared to experimental measurements of the Brillouin gain spectrum (BGS), carried out using a Brillouin optical frequency-domain analysis (BOFDA) configuration operating at 1550 nm wavelength and featuring a spatial resolution as low as 5 mm. The fabricated sensors are promising platforms for quasi-distributed refractive index measurements.