All-optical label processing techniques for pure DPSK optical packets

We present two all-optical label processing schemes for pure differential phase shift keying packets. The two techniques are based on the already used optical correlators and on a novel time-to-wavelength conversion of the label information. They require that the label information is encoded by using pulse position modulation, which makes the label processor simpler and can allow very fast processing speed. We investigate and compare the efficiency in terms of packet overhead of pulse position modulation coded labels with ordinary binary coding and show that pulse position modulation is still attractive for medium-size network and for system implementing optical label swapping. We then experimentally demonstrate that the two techniques can distinguish several labels at distinct outputs. Both operate at low optical power, asynchronously, and could allow for photonic integration. Scalability and processing speeds of the two systems are discussed. We also show that the two label processors can be used to implement an optical label swapping system. Experimental results show that the two labels are distinguished at two distinct ports and erased from the incoming packet, so that a new label can be inserted. Scalability and processing speed are discussed as well.