Full optical encoders/decoders for photonic IP routers

Photonic Internet protocol (IP) routers can support higher throughput and have lower end-to-end transfer delay, with respect to electrical IP routers. The IP addresses are directly mapped onto the optical layer and processed by performing optical correlations in the time domain between the incoming code and the entries of the address bank; a different tapped delay-line encoder/decoder (E/D) is used for each photonic label. In the present paper, an innovative compact low-loss full E/D is presented that generates/processes a set of orthogonal codes (OCs) simultaneously. A tree of Mach-Zehnder interferometers (MZIs) furnishes the whole set of photonic labels at the same time; it is also possible to add/drop labels without modifying the remaining code sequences. The correlation performances of the OCs can be further enhanced by inserting additional phase shifters in the MZI's arms.