On dynamic wavelength assignment in WDM optical networks

Optical fiber has been used as the physical medium for high rate data transmission since late 1960s. Early applications of optical fiber communications modulated data onto a single optical carrier frequency that is commonly referred to as a wavelength. The carried data rate is therefore limited by the speed of electronics that generate the signal, thereby grossly underutilizing the tens of THz of useful bandwidth available on the fiber[1]. The Wavelength Division Multiplexing (WDM) technology now allows multiplexing everal optical carriers on the same fiber, opening up the available potential. Current deployments of WDM are based on point-to-point links. This entails demodulating the optical signal at each switching node and carrying out switching electronically. Remarkable increase in the carried data rates due to the WDM technology make these switches inherent bottlenecks in the network. One promising approach to solve this problem is optical switching which entails switching entire wavelengths without any electronic processing.