The Technology and Architectures Behind Optical Networks

This section briefly outlines the current architectures of optical networks. It also serves to filter out from the rest of the discussion directions that are beyond the scope of this section.

Optical networks can be divided according to the following taxonomy:

·        Wavelength division multiplexing (WDM)

·        Short-pulse optical time division multiplexing (OTDM).

·        Optical code division multiplexing (OCDM)

The main distinction between the various network types is based on the multiplexing scheme: whether it is done in the frequency domain (WDM) or the time domain, as in optical time division multiplexing (OTDM), or in OCDM. WDM networks may be further split into:

·        Point-to-point links -- in which both ends of the link have identical equipment to transmit and receive the channels

·        Access networks -- in which one side of the link gets split among different locations and requires simpler equipment at the customer.

·        Broadcast-and-select systems--in which the signal is broadcast to multiple endpoints rather than a single endpoint

·        More scalable and complex networks, in the form of wavelength routing networks, realized by introducing switching nodes to connect multiple point-to-point WDM links