Thin co-axial and thick co-axial cables have conductive grounding sheath surrounding the center conductor. Therefore, the electromagnetic interference (EMI) is significantly less.
Fiber optic cabling is immune to crosstalk and other electrical interference because optical fiber does not conduct electricity and uses light signals in a glass fiber, rather than electrical signals along a metallic conductor to transmit data. So it cannot produce a magnetic field and thus is immune to EMI.
In twisted pair cable, the noise introduced into the twisted pair wire is canceled as the electrical signals pass through the wire. However, it is not possible to reduce the electrical interference totally in a TP wire .Instead of transferring data over copper wires, these cables contain optical fibers that transmit data via light, rather than pulses of electricity. Each optical fiber is individually coated with plastic layers and contained in a protective tube, making it extremely resistant to external interference.
Twisted Pair cable Types:
STP stands for Shielded Twisted Pair and UTP stands for Unshielded Twisted Pair.
Shielded Twisted Pair (STP)cables reduce electrical noise and electromagnetic radiation. In other words, they help to keep the signal steady, and reduce interference with other devices. Given below is a diagram showing a typical shielded twisted pair cable
Unshielded Twisted Pair (UTP)cables do not have shielding to reduce interference. They are designed to cancel electromagnetic interference with the way the pairs are twisted inside the cable. Unshielded twisted cables are most widely used for office LANs, though recently wireless LANs are more widely used. Unshielded cables are lightweight, thin and flexible. They are also versatile and inexpensive. A typical UTP cable cross section is shown in the figure below: