Diseño de un láser de fibra óptica de alta intensidad para mejoramiento del proceso de depósito supersónico laser

Abstract

This thesis reports the characteristics of the design of laser generation by means of a double‐clad ytterbium‐doped optical fibre. An octagonal shape for the inner clad has been proposed to improve the energy pump absorption. The functioning scheme of the fibre laser (FL) follows the “all‐fibre” configuration utilizing Bragg gratings and multi‐mode couplers as reflector devices to inject the pump light. The laser was proposed to improve the Supersonic Laser Deposition (SLD) process, which has been used in the production of films based on metallic powders. Presently, the SLD employs a 4 kW FL of IPG Photonics and it does not reach the expected efficiency by the developers of this technique The low productivity is due to the low adherence that exists in the zones located close to the gas‐powder fingerprint that is left by the particle acceleration system of the SLD. For the above reason, the design of the FL was based on the analysis of the heating needs of three materials of interest: aluminium, low carbon steel and titanium. The result obtained was that the Gaussian beam profile is not adequate to achieve uniform heating, and it was found that Horseshoe profile produces better results. In order to accomplish the Horseshoe profile, two‐Axicon lens were employed to modify the beam emitted by the FL. Thus, the characteristics that the FL should posses to energize a substrate to 900°C were obtained. The results of the analysis of the FL by simulation show that the proposed fibre does not reach the heating power that the SLD needs.. It is necessary to modify the characteristics of the FL in order to raise the emission power levels and the emergence of nonlinear phenomena and thermo‐optic damage limits that can degrade the fibre. For this reason, it will be necessary to establish in future work the enhanced geometric profiles of the fibre and rare‐earth doping concentration in the core in order to validate the results presented here and to comply with requirements imposed by the SLD process. Due to the limited availability of the infrastructure where the SLD process is developed, the work achieved was also limited to simulation and the analysis of these results. However, they are of great help for the continuation of a deeper study of this subject.