Device for spatial demultiplexing of an incident optical beam (Fid) and for coherent recombination of N elementary beams (F 1, F 2,..F N) from the resampling of said incident beam (Fid) having undergone a distortion, the spectrum of said incident beam comprising M wavelengths (λ 1, λ 2,...λ M) each constituting a channel for conveying a piece of information, the device comprising: - a device for spatially demultiplexing the incident beam (Fid) configured to sample said incident beam in N elementary beams (F 1, F 2,..F N), - a device for coherently recombining the N elementary beams, N being a strictly positive even integer number, comprising a plurality of elementary devices arranged in cascade so as to obtain a single recombinant beam (Frecomb), an elementary device for coherent recombination recombining a first and a second elementary beam, said distortion having induced a delay (R 12) between said first and second elementary beams, the elementary device comprising: - a first input (Input1) and a second input (Input2) into which are respectively injected the first and the second elementary beam to be recombined, - an output (Out) delivering an output beam corresponding to the coherent recombination of the first and of the second elementary beam, - a delay line placed on one of the paths of said elementary beams and configured to induce a variable delay on said path, - a variable coupler comprising a first 2x2 combiner (Comb), a phase modulator placed on one of the two outputs of the first combiner and a second 2x2 combiner (Comb'), the second combiner having a main output that forms the output (Out) of the elementary device and that delivers said output beam and a complementary output (Sc) that delivers a beam that is complementary to the output beam, - a control detector (Det) connected to the complementary output (Sc) configured to generate, from the complementary beam, an error signal (ε) which is canceled when the phase modulator is configured to apply a phase difference that equalizes the intensities of the first and second elementary beams, and when the delay line is configured to apply a delay that compensates for said delay (R 12) between said first and second elementary beams, - a control loop configured to determine, from the error signal, the delay and the phase difference to be applied. - a device for spatially demultiplexing the incident beam (Fid) configured to sample said incident beam in N elementary beams (F 1, F 2,..F N), - a device for coherently recombining the N elementary beams, N being a strictly positive even integer number, comprising a plurality of elementary devices arranged in cascade so as to obtain a single recombinant beam (Frecomb), - a first input (Input1) and a second input (Input2) into which are respectively injected the first and the second elementary beam to be recombined, - an output (Out) delivering an output beam corresponding to the coherent recombination of the first and of the second elementary beam, - a delay line placed on one of the paths of said elementary beams and configured to induce a variable delay on said path, - a variable coupler comprising a first 2x2 combiner (Comb), a phase modulator placed on one of the two outputs of the first combiner and a second 2x2 combiner (Comb'), the second combiner having a main output that forms the output (Out) of the elementary device and that delivers said output beam and a complementary output (Sc) that delivers a beam that is complementary to the output beam, - a control detector (Det) connected to the complementary output (Sc) configured to generate, from the complementary beam, an error signal (ε) which is canceled when the phase modulator is configured to apply a phase difference that equalizes the intensities of the first and second elementary beams, and when the delay line is configured to apply a delay that compensates for said delay (R 12) between said first and second elementary beams, - a control loop configured to determine, from the error signal, the delay and the phase difference to be applied.