Abstract: The invention concerns a numerical calculation procedure of the diffraction of a structure (1) whose numerical model defines the dielectric permittivity at each point comprizing the steps of: definition of a numerical modellization of the diffraction model of a structure including: the splitting of the numerical model of the dielectric permittivity into N numerical models of dielectric permittivity; the determination of the diffraction model of the said layers from the numerical model of this layer; numerical calculation of the diffraction of the structure including: an initial iteration during which one performs: one wave propagation in the direction of layers 1 to N, and one wave propagation in the direction of the layers N to 1, ulterior iterations, each ulterior iteration of index k including: one wave propagation in the direction of layers 2 to N: one wave propagation in the direction of layers N?1 to 1.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.

Abstract: For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.