Optoelectronic Switching for Virtual Wavelength Paths

Abstract

Optical transmission with wavelength division multiplexing (WDM) opens the possibility of "transparent" networks that can carry virtually any signal between any pair of network terminals. The advantages for upgrading, reconfiguration and service provision are obvious. Foreseeable WDM technology provides only a few tens of wavelength channels for use in the whole network. These are most efficiently used if wavelength assignments can be independently made on each link. A nodal "wavelength crossconnect" (WXC) function is then required to assign new wavelengths to the incoming signals on outgoing links. If this function can be done transparently a "Virtual Wavelength Path", analogous to the "virtual path" concept of ATM routing is created. However methods of wavelength translation that provide optical transparency tend to be expensive, polarization dependent, hungry for optical power, and in an immature state of development.