information demand in the internet world is creating enormous needs for capacity
expansion in next generation telecommunication networks. It is expected that the
data- oriented network traffic will double every year.Optical
networks are widely regarded as the ultimate solution to the bandwidth needs of
future communication systems. Optical fiber links deployed between nodes are capable
to carry terabits of information but the electronic switching at the nodes limit
the bandwidth of a network. Optical switches at the nodes will overcome this limitation.
With their improved efficiency and lower costs, Optical switches provide the key
to both manage the new capacity Dense Wavelength Division Multiplexing (DWDM)
links as well as gain a competitive advantage for provision of new band width
hungry services. However, in an optically switched network the challenge lies
in overcoming signal impairment and network related parameters. Let us discuss
the present status, advantages and challenges and future trends in optical switches
fiber consists of a glass core and a surrounding layer called the cladding. The
core and cladding have carefully chosen indices of refraction to ensure that the
photos propagating in the core are always reflected at the interface of the cladding.
The only way the light can enter and escape is through the ends of the fiber.
A transmitter either alight emitting diode or a laser sends electronic data that
have been converted to photons over the fiber at a wavelength of between 1,200
and 1,600 nanometers.Today fibers
are pure enough that a light signal can travel for about 80 kilometers without
the need for amplification. But at some point the signal still needs to be boosted.
Electronics for amplitude signal were replaced by stretches of fiber infused with
ions of the rare-earth erbium. When these erbium-doped fibers were zapped by a
pump laser, the excited ions could revive a fading signal. They restore a signal
without any optical to electronic conversion and can do so for very high speed
signals sending tens of gigabits a second. Most importantly they can boost the
power of many wavelengths simultaneously.