Subchannel photonic routing, switching and protection with simplified upgrades of wdm optical networks

Abstract

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of the client circuits mapped to these subchannels across the nodes of a WDM network.

What is claimed is: 
     
         1 . A system to route client signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the system comprising:
 one or more optical subchannels, each optical subchannel corresponding to a separate laser operating at a distinct optical carrier frequency, wherein the optical carrier frequency at which the laser is operating for at least one subchannel is offset from an International Telecommunication Union, Telecommunication Sector (ITU-T) grid;   a first network route that designates an origin of the one or more optical subchannels at a first node, and a destination for the corresponding one or more optical subchannels at a second node, wherein the first network route to transmit one or more of the client signals; and   a subchannel mapper to map at the first node the one or more of the client signals to the one or more optical subchannels.