In our days, the most advanced transmission medium and the only one capable of supporting next generation services are the fiber optic cables. The fundamental points of interest of having a last mile of optical fiber are many; we name a few:
Higher bandwidth,Longer distances from the central to the subscriber,More resistance to electromagnetic interference,Increased security,Reduced signal degradation…
Moreover, the fact of using Passive Optical Network (PON) technology, expect the disposal of repeaters or regenerators and optical amplifiers; therefore reducing the initial investment, lowering power consumption, reduction in space occupation, and fewer points of failure.
The dominance of broadband applications such as high definition television (HDTV) broadcast, broadband Internet access or tele-working, teleconferencing, has made a developing enthusiasm among service providers to supply broadband services to residential and small businesses. Service providers should consider a high efficiency between the total cost of infrastructure and services that can be offered to end users.
The Wavelength Division Multiplexing (WDM) and Dense Wavelength Division Multiplexing (DWDM) are the technologies that can convey the best solution for long distance applications.
In the meantime Coarse Wavelength Division Multiplexing (CWDM) is considered the perfect solution for get to networks and metropolitan areas. CWDM is a method of consolidating multiple signals on laser beams at various wavelengths for transmission along fiber optic cables, such that the number of channels is less than in dense wavelength division multiplexing (DWDM). For example, CWDM utilizing a channel spacing of 20 nm can relax the tolerances of the components used, such as filters, multiplexers and de-multiplexers, routers or switches and the operating characteristics of the active components such as lasers.