The paper presents the simulation results for an optical system based on a high-power and high-brightness laser module. The module design implies spatial and polarization combining of beams from 24 single-emitter laser diodes. The theoretical design and computational simulation were conducted for the fiber-coupled optical system with the fiber of 200/225 µm in diameter and numerical aperture of 0.22. The coupling efficiency is 89% which correlates with the results of experiments with the laboratory module prototype.