Failure of multimode optical fibers nano-structured by near ablation threshold single-shot femtosecond laser procedure

Abstract

The present paper deals with the study of the failure probability of nano-structured optical fibers when submitted to uniaxial tensile loading. A nano-structuration procedure of optical fibers thanks to near ablation threshold single shot femtosecond laser has been proposed. The ablation threshold energy Ep0 for silica fiber is such that: NA2Ep0=15.5nJ, where NA is the numerical aperture of the objective to focus the laser inside the fibers. The rupture strength of the impacted fibers can be controlled through the pulse energy Ep, the numerical aperture NA, the number Nl of nano-craters depending on the step dz of the position of the fiber surface into the focal region, the interval dx between each crater and the number nl of flaw lines. An additive combination of two classical Weibull's laws allows a good representation of the failure probability of the impacted fibers. A phenomenological model for the evolutions of the Weibull's parameters (exponents and scaling stresses) has been proposed and the experimental tendencies of the failure probability curves are fairly well described by the set of the model's equations (Eq. (27)).