What is Fiber Optics?
Fiber optics refers to the technology and method of transmitting data as light pulses along a glass or plastic strand or fiber. Fiber optic cables are used for long-distance and high-performance data networking. They are capable of transmitting data over longer distances and at higher bandwidths (data rates) than electrical cables, making them a critical component in modern telecommunications, internet, and computer networking.
Main Elements of Fiber Optics
Core: 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.
Cladding: It is an outer optical material surrounding the core having a reflecting index lower than the core and cladding helps to keep the light within the core throughout the phenomena of total internal reflection.
Buffer Coating: 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.
Types of Fiber Optics
There are different types of fiber optics based on several categories as mentioned below:
1. Based on the Number of Modes
Single-mode fiber: In 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 refractive index of core and cladding is very small. There is no dispersion i.e. no degradation of the signal during traveling through the fiber. The light is passed through it through a laser diode.
Multi-mode fiber: Multimode 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. Step Index Fiber and Graded Index Fiber. These are categories under the types of optical fiber based on the Refractive Index
2. Based on Refractive Index
Step-index optical fiber: The refractive index of the core is constant. The refractive index of the cladding is also continuous. The rays of light propagate through it in the form of meridional rays which cross the fiber axis during every reflection at the core-cladding boundary.
Graded index optical fiber: 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
Plastic Optical Fibres: For transmission of light, polymethylmethacrylate is used as core material
Glass Fibres: These are extremely fine glass fibers, the core and cladding of the optical fiber is made of plastic.