I. Introduction
Optical technology is effectively increasing the networks capacity and is widely applied in the point-to-point connections, where the capacity of the optical fiber links is exploited with the wavelength division multiplexing (WDM) technique. Nevertheless the present optical communication networks operate optical-electrical-optical (OEO) conversion at the nodes to perform signal routing and regeneration. The continuous increasing of the bandwidth demand due to the raising of broadband Internet services, e.g., video on demand, needs to increase the network capacity and complexity. One of the most critical element is the node, where the traffic has to be received, regenerated, added/dropped and routed to the proper output port. A bottleneck is represented by the huge power consumption and wiring density of the IP routers [1]. Optical packet switched (OPS) networks are becoming attractive because they allow packet routing without OEO conversion of the data, which makes the network transparent to the data format and reduces the packet latency time. A considerable effort has been done to increase the number of functionalities to be implemented in the optical domain at the network nodes such as regeneration, adding/dropping, and buffering. Complex functions in the optical domain enable high bit rate signal processing indeed. In [2]–[4] demultiplexing from OTDM frames up to 640 Gb/s is demonstrated. Add/drop is demonstrated in [5]–[7] up to 160 Gb/s. All-optical regeneration is demonstrated and investigated in [8]–[10] with optical fibers and in [11], [12] with SOAs.