Multi-plane conversion device

A multi-plane conversion device of a first light radiation, the device having a conversion block comprising a plurality of optical parts and implementing a plurality of phase masks supported by at least one of the optical parts, the phase masks applying a spatiofrequential phase shift for producing a second light radiation, a predetermined transformation, known as a transformation with separable variables, linking N modes of index {i, j}k, 1<=k<=N, of a first used mode family with separable spatial variables (x,y) describing the first light radiation in a first transverse plane with N modes of the same index {i, j}k 1<=k<=N, of a second used mode family with separable spatial variables (x,y) describing the second light radiation at a second transverse plane, the N modes of the second used mode family not being Hermite-Gaussian modes and, at the same time, the N modes of the first used mode family not being arranged in the first transverse plane in the form of a triangle.