Expérimental et théorique
Coherent Beam Combining (CBC) of fiber lasers is a promising technique to scale-up peak and average powers of laser systems with beam shaping capabilities. XCAN is a CBC fs fiber digital laser based on 61 tiled channels stacked in a hexagonal arrangement and operating in both high peak & average power regimes. Tiled aperture offers high agility in terms of far field beam shaping as each channel is seen as an individual pixel where amplitude & phase are controlled independently. However, the periodic intensity distribution of the array beams in the near field gives rise to low-intensities side-lobes. Thus, the combined beam corresponds only to the main lobe of the far field pattern. The combining efficiency is defined as the power in this central lobe over the average power in the far field. The aim of this internship is to explore different phase, intensity and polarization patterns as a tool for far field shaping on demand and to further improve the efficiency achievable with tiled aperture CBC. The candidate shall investigate patterns capable of re-steering the maximum of energy into the main lobe. He/she will develop codes for CBC numerical simulation. Iterative computing approaches like the Gerchberg-Saxton algorithm, deep learning, neural network and genetic algorithms allow computing the required phase and intensity modulation to be applied on the near field to produce a predefined target far field distribution. Experimental demonstration on XCAN shall be performed.