Photonics for switching and routing

The ongoing growth of data traffic from existing and new applications poses a challenge to the packet-switched network infrastructure. High-capacity transport can be achieved in such networks by using dense wavelength-division-multiplexed systems, and reconfigurable optical add-drop multiplexers allow the optical layer to provision wavelength-based circuits between routing nodes. However, construction of the high-capacity packet routers provides significant scaling issues due to complexity, interconnect, and thermal limits. In this paper we will not seek to cover all aspects of optical packet switching and routing but outline some of the challenges facing the construction of such future routers and describe the role photonics can have in overcoming some of these issues. We will discuss how photonics' primary role will be to provide interconnection between racks of electronic routing elements and describe how fast wavelength switching can provide a high-capacity distributed switch fabric that will allow these packet routers to scale to higher capacities. The fast wavelength switching can be seen as the packet analog of wavelength-based circuit switching of today's transparent optical networks.