An optical demultiplexer includes an interleaver with at least four ports including a first port adapted to receive the sum of two optical signals A and B, a second port and a third port respectively for signals A and B, and a fourth port. The optical demultiplexer further includes an optical component coupled to at least one of the two ports for signals A and B and configured to split the optical signal to be outputted into a weak intensity optical signal and a strong intensity optical signal.