Device for processing light radiation, comprising a multi-plane light conversion device

A device for processing light radiation, comprising:

• an optical input for receiving an input beam from an optical source and for propagating an input radiation in the device, said input radiation being described in a base of input modes, referred to as the input mode base, which input modes are not entirely spatially disjointed;
• an optical output for emitting an output beam;
• a multi-plane light conversion device arranged between the optical input and the optical output and configured to transform the input mode base into an output mode base while ensuring that one particular input mode, referred to as the assumed input mode, is transformed into a particular output mode, referred to as the target mode, the multi-plane light conversion device also being configured to spatially separate, in a separation plane, the input radiation into useful radiation, in the target mode, the useful radiation propagating to the optical output and into an interference radiation;
• and
• at least one blocking device for blocking the interference radiation, the at least one blocking device arranged in the separation plane so that it does not contribute to the output beam.