Optical Networking Technology
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Who needs more bandwidth?
Increased bandwidth demand will arise from a proliferation of applications such as data and call centers, as well as by the bootstrapping effect of increased consumption resulting from lower rates. For example, if the STD charges are reduced to one tenth of what they are today, I still do not expect to see my phone bill go down because my wife’s phone calls will just become ten times longer

Optical Communication
Optical communication is the transfer of signals from one point to another using optical fiber as the communication medium. Simply put, optical fiber is an extremely thin, glass pipe that has an enormous communication capacity. The communication is effected by turning a light source, usually a laser, ‘on’ to indicate a ‘1’ bit and ‘off’ to indicate a ‘0’ bit. The rate at which the laser is turned on and off is the rate of communication


DWDM
As the communication needs (traffic) increased, the capacities of the fiber communication systems have had to keep pace. Initially this was accomplished by increasing the bit rate from 155 Mb/s to 622 Mb/s, then to 2,488 Mb/s, and finally to 10 Gb/s. (1 Gb/s = 1000 Mb/s.) These are the standard rates of the synchronous digital hierarchy, or SDH, networks, that are widely deployed globally, including in India. A higher rate SDH stream carries a number of lower rate SDH streams by interleaving them in time.

Optical Amplification
It is possible to send each signal over a different fiber rather than at a different wavelength over the same fiber, thus avoiding the use of DWDM. However, such a multifiber solution, which amounts to the use of multiple SDH networks in parallel, is inefficient, for the following reason.