1. A method for converting digital electrical data into modulated optical streams, said method comprising inputting into an optical modulator N bits of digital data in parallel, N being larger than 1; mapping a set of N input values corresponding to said N bits of digital data to a vector of M voltage values where M is equal to or larger than N; driving at least M electrodes of the optical modulator, enabled to pulse modulate at least an input optical stream, responsively to the M voltage values, to provide at least a pulse modulated output optical stream.