The effect of current spreading on the lateral far-field divergence of high-power broad-area lasers is investigated with a time-dependent model using different descriptions for the injection of carriers into the active region. Most simulation tools simply assume a spatially constant injection current density below the contact stripe and a vanishing current density beside. Within the drift-diffusion approach, however, the injected current density is obtained from the gradient of the quasi-Fermi potential of the holes, which solves a Laplace equation in the p-doped region if recombination is neglected. We compare an approximate solution of the Laplace equation with the exact solution and show that for the exact solution the highest far-field divergence is obtained. We conclude that an advanced modeling of the profiles of the injection current densities is necessary for a correct description of far-field blooming in broad-area lasers
