A wavelength-routing node by using multifunctional semiconductor optical amplifiers and multiple-pilot-tone-coded subcarrier control headers

Wavelength-division-multiplexing (WDM) can dramatically increase the capacity of optical networks through simultaneous transmission of multiple channels on the same fiber. Furthermore, a wide-area WDM network may be composed of many local-area WDM networks, with certain wavelengths accessing the WAN and certain other wavelengths accessing each LAN. For a WDM access node at the WAN-LAN gateway, a wavelength routing function is required: if the data packets are destined for this LAN, they will be dropped and wavelength shifted to the appropriate wavelengths, otherwise, they will pass through the access node unaffected. Recent work has reported the dynamic wavelength shifting by using an 8-bit 50-Mbit/s-modulated subcarrier control header.