**1. Introduction**

From the exponential popularity of Internet and its derived new services, recently deployed communication networks should be capable to provide more information throughput than ever. On a recent study [1], CISCO has estimated that global Internet traffic has increased by a factor of height over the past five years and will increase nearly by a factor of four over the

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

next five years, with an annual global Internet protocol (IP) traffic exceeding the tens of zettabyte mark by the end of 2017.

High definition (HD) streaming video and peer-to-peer applications use the majority of bandwidth in most broadband networks today. When we add the bandwidth requirements of online social networks, Internet browsing or online gaming, broadband service providers have to supply an increasingly larger amount of bandwidth. Besides human-made Internet traffic, machine-to-machine (M2M) communications [2], fostered by smart city applications [3] and the opening of new radio channel opportunities [4] are spreading globally. The Internet of things (IOT) [5] will contribute even more to increase the quantity of data exchanged in communication networks, and especially on optical communication networks, used both by wireless and cable communications.

Photonics technologies have largely contribute to the considerable development of telecommunication networks, since they appearance 30 years ago, and one can predict that they will serve as ground for most of the network revolutions still to come. A recent study [6] of the drivers of photonics suggests that its future development will be made along four main paths: to make optical networks faster, more transparent, more dynamic and greener. With current technology, it may be difficult to follow simultaneously all four path, which is a major constrain to implement a novel generation of optical networks. However, these difficulties may be relieved by recent developments in the field of wavelength conversion, all-optical signal processing and flexible techniques to generate enhanced modulation formats in optical signals.

In this context, this chapter presents several techniques on format conversion of modulated signals, using Mach-Zehnder interferometers with semiconductor optical amplifiers (MZI-SOA). The MZI-SOA show very attractive properties, and therefore, the goal is to investigate their potential as an optical node for the dynamic conversion and generation of optical signals. As such, two techniques to implement all-optical modulation format conversion are explored. These techniques, when applied in interconnection nodes between different optical networks with variable bit rates and modulation systems, allow a better efficiency and scalability of the network.
