Future photonic transport networks based on WDM technologies

It is expected that the explosion in Internet traffic implies a paradigm shift from a voice network to a data-centric network. The first and most important requirement of future transport networks is the large bandwidth transport capability which enables the paradigm shift. In addition, requirements for new service attributes are becoming more tangible. Furthermore, high reliability will be indispensable because the multimedia network will be the basis for the information society. To develop the robust and efficient networks that satisfy the requirements above, new network architectures and technologies should be developed. Photonic networks employing dense WDM technologies appear to be the solution. In this article, first the basic concept of the future photonic network is depicted. Next, the capability of large-capacity fiber transmission is shown. The critical degradation factor of fiber nonlinearity is analyzed, and the effectiveness of distributed amplification is quantitatively demonstrated. Furthermore, advances in fiber amplifiers which greatly widen the usable fiber window are shown. Other key technologies such as absolute frequency referencing and multiple channel frequency management techniques are also discussed.