An optical transmitter for transmitting a vector of information symbols over an optical fiber transmission channel made of a multi-core fiber, optical signals carrying the vector of information symbols propagating along the multi-core fiber according to two or more cores, wherein the optical transmitter includes a precoder configured to determine a precoding matrix depending on one or more fiber parameters associated with the multi-core fiber and to precode the vector of information symbols by multiplying the vector of information symbols by the precoding matrix.