Modern Optical Networks - Optical Signal Processing by Silicon Photonics - page 22

Fig. 3.2 Transmission media classification
fluctuations in the refractive index scatter light in all directions. Another loss fac-
tor is the bending loss which may scatter light at the core-cladding interface. In
communication systems the splicing loss and connector losses may also contribute
to the attenuation of the transmitted light (Fig. 3.2 ).
3.3 Transmission Media
• Guided media: that provides a medium from one device to another. For example
twisted-pair, coaxial cable, and optical fiber.
• Unguided media/wireless communication: that transfers electromagnetic waves
without using a physical conductor. As a substitute, signals are broadcast
through air (or, in a few cases, water), and thus are offered to anyone who has a
device capable of receiving them.
3.4 Communication Media
The communication media is briefly divided as under on the basis of the physical
structure required for it.
3.4.1 Wired Technologies
Twisted-pair is generally the most common medium used for telecommunication.
In twisted-pair cabling, the copper wires are twisted to form pairs, the typical tel-
ephone wires consist of two insulated copper wires twisted into pairs. In computer