Link Design and Legacy Amplifier Limitation in Flex-Grid Optical Networks

Flex-grid technology is an effective mean to improve the spectral efficiency of optical communications. For a given amplifier spectral bandwidth, it gives rise to the increase of the number of optical channels as it reduces the channel spacing. Therefore, in order to reap full benefits from flex-grid saved spectrum, further amplification power is required with respect to conventional fixed grid. This is a strong limitation if the legacy amplifiers cannot meet this new requirement due to their optical power limits. In this work, we demonstrate that exploiting the link margins allows supporting this increase while maintaining in use legacy amplifiers.