Photonic encoder and decoder for optical code-division multiplexing with time-to-space converters and angle-multiplexed holograms

A photonic encoder–decoder pair for optical code–division multiplexing (OCDM) that uses time-to-space converters and angle-multiplexed holograms is proposed. The encoder converts the pulse from each input port into a specific code and multiplexes input signals into the output port. The hologram in the decoder generates a correlation waveform between the transmitted code and the recorded code. The performance of the OCDM system with the encoder–decoder pair is estimated. The maximum spectral efficiency for 8-bit length orthogonal codes in the worst case at a bit-error rate of 10^-9 is 0.17 (bits/s)/Hz when the number of channels is 8.