Optical breakdown of a fiber in the case of a non-ideal contact with the initiator

Abstract

This article describes a mathematical model of optical breakdown at the end of an optical fiber in the case of a non-ideal contact between the end of the optical fiber and the initiator surface. An air gap was assumed between the fiber end face and the initiator. The model was based on a heat conduction equation in cylindrical coordinates. The air motion in the gap was described by equations of free convection in the Boussinesq approximation, taking into account the thermal radiation arising at the optical fiber end face and at the initiator section opposite the fiber, where the radiation reflection occurs. As a result, temperature fields were obtained. The characteristic times of evolution of the plasma formation region and the threshold power of optical breakdown were determined on the basis of the temperature fronts boundaries. It is concluded that convection has a weak effect on heat dissipation during optical breakdown in a fiber compared to other mechanisms of heat transfer.