An apparatus for optical processing of a signal includes an optical sampler, an optical neural network and a phase shift controller. The optical sampler obtains parallel optical samples by sampling a continuous optical signal. The optical neural network optically processes the parallel optical samples and provides a final output optical signal resulting from the processing. The optical neural network includes interconnected optical neurons. Each of the optical neurons inputs multiple optical signals and outputs an optical signal which is a weighted sum of the input optical signals. The weightings are established by phase-shifting the input optical signals prior to the summation. The phase shift controller controls the phase-shifting so as to obtain required weightings for the input optical signals.