Tensile strain dependence of the Brillouin gain spectrum in carbon/polyimide coated fibers.

The strain dependence of Brillouin gain spectrum in two novel carbon/polyimide coated fibers (CPCFs) is studied, for what we believe to be the first time, by numerical simulation and experiment. The strain dependence of the Brillouin frequency shift for the two CPCFs maintained linear relation with the elongation up to 4.26% and 4.0%, respectively. The effects of strain on the elastic modulus, the core refractive index, and density are determined, which have been used to simulate the strain dependence of the frequency shift, linewidth, and gain coefficient for the two CPCFs. The simulated and measured results are well matched.