Network structure
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Fiber optic networks transmit light through optical fibers to communicate over long distances at high bandwidth. An optical fiber consists of a cylindrical glass core surrounded by a cladding layer of glass or plastic with a lower refractive index. This structure allows light to propagate along the core through total internal reflection. Fibers have a small single-mode core or larger multimode core. Single-mode fiber has lower attenuation over long distances while multimode can transmit more data over shorter runs.
Network structure
- 2. FIBER OPTIC NETWORK An optical fiber (or optical fibre) is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables.
- 4. The basic structure of an optical fiber consists of three parts; the core, the cladding, and the coating or buffer. The core is a cylindrical rod of dielectric material. Dielectric material conducts no electricity. Light propagates mainly along the core of the fiber. The core is generally made of glass. The core is described as having a radius of (a) and an index of refraction n1. The core is surrounded by a layer of material called the cladding. BASIC STRUCTURE OF AN OPTICAL FIBER
- 5. The cladding layer is made of a dielectric material with an index of refraction n2. The index of refraction of the cladding material is less than that of the core material. The cladding is generally made of glass or plastic. The cladding performs the following functions: Reduces loss of light from the core into the surrounding air Reduces scattering loss at the surface of the core Protects the fiber from absorbing surface contaminants Adds mechanical strength For extra protection, the cladding is enclosed in an additional layer called the coating or buffer. The coating or buffer is a layer of material used to protect an optical fiber from physical damage. The material used for a buffer is a type of plastic.
- 7. Single Mode fiber optic cable has a small diametric core that allows only one mode of light to propagate. Because of this, the number of light reflections created as the light passes through the core decreases, lowering attenuation and creating the ability for the signal to travel faster, further. This application is typically used in long distance, higher bandwidth runs by companies, and Colleges and Universities.
- 8. Multimode fiber optic cable has a large diametric core that allows multiple modes of light to propagate. Because of this, the number of light reflections created as the light passes through the core increases, creating the ability for more data to pass through at a given time. Because of the high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced over long distances. This application is typically used for short distance, data and audio/video applications in LANs.
- 10. For an optical fiber, a step-index profile is a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the core-cladding interface so that the cladding is of a higher refractive index. In fiber optics, a graded-index fiber is an optical fiber whose core has a refractive index that decreases with increasing radial distance from the fiber axis (the imaginary central axis running down the length of the fiber).
- 12. SATELLITE NETWORKS In satellite communication, signal transferring between the sender and receiver is done with the help of satellite. In this process, the signal which is basically a beam of modulated microwaves is sent towards the satellite. Then the satellite amplifies the signal and sent it back to the receiver’s antenna present on the earth’s surface. So, all the signal transferring is happening in space. Thus this type of communication is known as space communication.
- 14. CELLULAR NETWORK Cell site is a geographical area that is circular in shape and caters to cellular phones insides its defined physical boundary. A cellular network consists of overlapped cells so that a larger area with low probability of call dropping may be provided. The overlapping in the structure ensures that the call is kept uninterrupted when the user changes his position from one cell site to the other.