are used for long-distance and high-performance ,.
It is the central tube of very thin size made of optically transparent dielectric medium and carries the light transmitter to receiver and the core diameter may vary from about 5um to 100 um.
It is a plastic coating that protects the fiber made of silicon rubber. The typical diameter of the fiber after the coating is 250-300 um.
1. Based on the Number of Modes
Single-mode fiber:single-mode fiber, only one type of ray of light can propagate through the fiber. This type of fiber has a small core diameter (5um) and high cladding diameter (70um) and the difference between the
Multi-mode fiber: allows many modes for the light rays traveling through it. The core diameter is generally (40um) and that of cladding is (70um). The relative refractive index difference is also greater than single-mode fiber. There is signal degradation due to multimode dispersion. It is not suitable for long-distance communication due to the large dispersion and attenuation of the signal. There are two categories based on Multi-mode fiber i.e.
2. Based on Refractive Index
Step-index optical fiber: propagate through it in the form of meridional rays which cross the fiber axis during every reflection at the core-cladding boundary.
In this type of fiber, the core has a non-uniform refractive index that gradually decreases from the center towards the core-cladding interface. The cladding has a uniform refractive index. The light rays propagate through it in the form of skew rays or helical rays. it does not cross the fiber axis at any time.
3. Based on the Material Used