Acoustic coefficients of P_2O_5-doped silica fiber: the strain-optic and strain-acoustic coefficients

Abstract

We present measurements and modeling of the effect of P2O5 doping on the strain sensitivity coefficients of silica fibers. In particular, the Brillouin gain spectrum of a heavily P2O5-doped fiber is measured and investigated at different strains. We provide measurements of the strain-optic coefficient (SOC) and the strain-acoustic coefficient (SAC), obtained to be + 0.139 and + 9854m/sec/e, respectively, both of which are less than the pure silica values. The Pockels’ coefficients p11 and p12 for bulk P2O5 are also estimated via Brillouin gain measurements. Using the strain coefficients, the modeled and unique slopes of the Stokes’-shift-versus-strain curves for the four observed acoustic modes in the fiber each lie within 2% of the measured values.