Multi-wavelength all-optical networks with wavelengths outside the erbium-doped fiber amplifier bandwidth

Erbium-doped fiber amplifiers have become the dominating technology for signal amplification in all-optical networks. One constraint of EDFA´s is that they have a much narrower bandwidth (≈25 nm) compared to the low-loss region (≈200 mn) of optical fiber. Instead of using only wavelengths within the bandwidth of EDFA´s (i.e. the inband channels) for communication, we propose to include wavelengths outside the EDFA bandwidth (i.e. the outband channels) as well in order to increase the number of wavelengths and/or channel spacings that can be accommodated. Using outband wavelengths for sending messages presents a new constraint, namely that only if the power loss for transmitting a message is small enough can this message be transmitted on the outband wavelength. We develop wavelength-routing algorithms on arbitrary network topologies and wavelength assignments in hierarchical networks for sending messages subject to this constraint. We also analyze the SNR for inband/outband WDM signals