Non-linear model for absorption in SiO2 optical fibres: Transport of concentrated solar energy

In order to determine the maximum solar energy than can be transported using SiO2 optical fibres, analysis of non-linear absorption is required. We propose a model based on Maxwellʹs equations and the Drude–Lorentz theory to determine the non-linear absorption for the maximum possible concentration ratio for circular concentrators. The relation between the electric susceptibility and the refractive index with microscopic parameters is provided. To solve the non-linear model for absorption experimental parameters are used. Our results estimate that the average value over the solar spectrum for the non-linear extinction coefficient for SiO2 is k2=10−29 m2 V−2. With this result we conclude that the non-linear part of the absorption coefficient of SiO2 optical fibres during the transport of concentrated solar energy achieved by a circular concentrator is negligible.