ing FPGAs, with the advantage that they allow working with volumes smaller than that necessary to fully justify the ASIC development expenses. 5.9 Interface Modules and Transceivers When optical transmission was born, optical systems were produced by vertically inte- grated companies, manufacturing in-house all the key components that should be inte- grated into the WDM system. Technology for Telecommunications: Integrated Optics and Microelectronics With the consolidation of the technology and the decrease of the margins due to the so-called bubble crisis, the companies in the optical communication market concentrated their effort on the core business, separating the activities in other areas. Contemporary to this market evolution, technology was going on producing more and more classes of different devices for different applications. Thus system vendors faced a double problem: first, it was difficult to develop in-house the electronic control of components that was manufactured outside; as a matter of fact, sometimes this is very hard without a direct knowledge of the mechanisms that are at the base of the component design (this is true, for example, for multi-section tunable lasers, several types of switches, and SO on). Moreover, in the absence of any standardization on the technology, every component has its own control and its own parameters; thus functionally equivalent components from different vendors cannot be exchanged, but each of them has to be driven by specific electronics. This fact makes it impossible for system vendors to leverage on multiple suppliers to have better prices and manage the risk that one of them faces the impossibility to go on with the furniture. In order to solve these two problems, system vendors started to ask components vendors for the so-called optical modules. These are subsystems that, in the simpler hypothesis, will contain a component with its own electronic control SO that this subsystem can be directly mounted on the system card and be driven by the system controller t