The invention relates to a switch (112) for optical signals and which has a number of outputs at least equal to the number of inputs and include means whereby an input signal is routed to at least one of those outputs. Each input receives information modulating optical carriers at different wavelengths. The switch (112) includes means (12611, 12612, . . . , 126NB) for grouping all the carriers received into non-contiguous subsets of carriers (G11, . . . , G1B, . . . , GN1, . . . , GNB) and means (1291, 1292, . . . , 129NB) for selecting blocks of carriers from the same subset of carriers. The information corresponding to each subset of optical carriers is thus routed in blocks to the same subset output. Switching the carriers at the subset level improves the quality of the output signal and limits the number of components for the same total quantity of information switched.