Basic of communication fiber optic

Fiber optical system must have transmitter, receiver and information channel. Block transmitter had information, before this information will to send must recognized match with channel information. And this information delivered to receiver used information channel.

Information channel have two part : Unguided channel and Guided channel. Example from unguided channel that is atmosphere where this system was use for radio, television and microwave relay links. Scope guided channels included few structure variant conduction transmission, like two wire line, coaxial cable and twisted pair

Message origin

Message origin there is information like non-electrical physical (audio and video), so that needed transducer (sensor) can change from non electrical to electrical, example : Microphone change sound become electrics, and video camera (CCD) change picture become electrics.

Modulator and carrier source

- Have two function, First change electrical message into appropriate form, Second joining this signal with others waving awakened by source carrier.

- Modulation can be different that is analog modulation and digital modulation.

- Modulation digital to joining with other signal and digital data in wave carrier, modulator must on or switch off carrier source match with data signaling.

Advantage fiber optical cable :

- Have big bandwith frequency

- Faster transmission digital information.

- Resistant with electromagnetic wave.

- Small damping more than copper cable.

- Physical is small and not heavily.

- Not have current electrical.

Disadvantage fiber optical cable:

- Cannot be folded.

- Its brittle materials.

- Maintenance must have specialization.

Introduction Fiber optic

Optical communication systems date back two centuries, that was begin from "optical telegraph" that French engineer Claude Chappe invented in the 1790s. His system was a series of semaphores mounted on towers, where human operators relayed messages from one tower to the next. It beat hand-carried messages hands down, but by the mid-19th century was replaced by the electric telegraph, leaving a scattering of "Telegraph Hills" as its most visible legacy. And Alexander Graham Bell patented an optical telephone system, which he called the Photophone, in 1880, but his earlier invention, the telephone, proved far more practical. He dreamed of sending signals through the air, but the atmosphere didn't transmit light as reliably as wires carried electricity. In the decades that followed, light was used for a few special applications, such as signalling between ships, but otherwise optical communications, like the experimental Photophone Bell donated to the Smithsonian Institution, languished on the shelf.

Fiber optic are essentially transparent rods of glass or plastic and it not flexible like metal cable. Diameter core optic not more 1 mm, it can transmission many information and not low loss information.

Core optical had protect by coating and cladding. Function core optical there is transmission for light wave, and core optical have refractive more better than coating and cladding because material it from transparent rods of glasses or plastic, diameter it about 2-125 μm (depend on optic type). Function cladding as fiber bodywork packer encircling core and refractive is low. Refractive at cladding low more than core, that is to make light in core keep focus until light receiver. Material of cladding that same with core but diameter more bigger than core between 5-250 μm (depend on optic type). Coating function is protect core and cladding, made from elastic plastic.

Difference of refractive of materials core and cladding, also damping or loss become important attention an optical fiber transmission system. Refractive useful in determining light coupling from optical source and useful in determining crept path of light variation of optical fiber. For the delivery light wave used infra-red area with wavelength 850-1600 μm. Damping of loss will have an in with determination apart maximum before repair of signal, smaller generated damping hence progressively the optical transmission the system is goodness.