 nature of optical circuits). This condition creates the need for a thermal control of the optical components, gener- ally carried out via a Termistor hosted inside the package. The final effect of these characteristics of optical packaging is that in several cases the cost of the package is higher than the cost of the integrated circuitry inside it. In the case of a DWDM DFB laser, for example, the package and the related elements are worth about 70% of the component Bill of Materials. 5.5.3.4 Integrated Optics Cost Scaling with Volumes The aforementioned reasons cause the cost model of integrated optics to be similar but not equal to that of microelectronics. This fact has been studied in particular in the field of optical access regarding the access line home termination. In this field, potential volumes on the order of millions are present on the market, apparently stimulating the development of an integrated optics platform. The variation of the cost of a component devoted to application in the optical access net- work is shown in Figure 5.31 versus the volumes for a microelectronic gigabit passive optical Normalized cost Discrete optics Microelectronics Integrated optics FIGURE 5.31 Price decrease versus volumes for a microelectronic GPON processor, a discrete optics GPON interface, Volumes (millions) and a monolithic integrated GPON interface. Telecommunication Networks network (GPON) processor, an integrated optics GPON interface, and a discrete optics GPON interface. The prices are normalized SO as to appreciate better the different trends. From the figure it is evident how the cost of integrated optoelectronic interface scales with volumes a bit faster with respect to the discrete optics components, but quite slowly with respect to microelectronic chips, due to the importance of the package Bill of Materials and the presence of important manufacturing processes serially executed component by component. 5.5.3.5 Integrated Planar III-V Components Even if in the absence of a radical technology breakthrough