Optical Transmitter
LED (Light Emitting Diode), LD (Laser Diode ), IL (Injection Laser), laser.

Optical Receiver
Avalanche Photo Diode (APD), P intrinsic N Diode (PIN-diode).

Fiber Optic cable
Step index or graded index, single or multi node glass, plastic clad silica, plastic connector SC, DIN, Straight Tail (ST), SMA, Fiber Optic Connector (FOC), Bionic.

Connectors
Mechanics, Thermal.

Accecories
T_connector, star connector, through connector, coupling.

Pigtail
Along the fiber optic cable with a connector on one end and the end the other is connected.

Patchcord
Along fiber optic cable with connectors on each end.

Coupler and Branches
Tools for graft light into two or more, Wavelength multiplexer.











System communication fiber opticFig1. System communication fiber optic.

Applications of fiber optics is not replaceable by the media other transmission. Because it can send data with the big bandwidth and have some advantages:

o cable and has a small capacity which is very large.
o Lightweight and flexible (not limited).
o There is no influence of electrical.
o Have a very long distance.
o High Security.
o Can be updated in the cable itself, to bring their own voltage.
o Safe from the explosion.
o No electro-mechanical interference.
o No crosstalk.
o No noise.

Bit data and distance















Fig2. Bit data and distance.

Silica glass, which is wrapping fiber optics in theory have strength by 14 kN / mm. In practice strength 7 kN / mm depending on the surface defect. Below is some type of optical fiber used in the application:

o System telecommunications regular grade index fiber 50 or 62.5 μm for the core /125 μm thick to thick.
o Industry graded index fiber 100 / 140 μmdan 200 / 240 μm.
o High Bandwidth distance single-mode fiber 8-12 / 125 μm.

Complete fiber optic structure consists of core / core wrapping (Cladding) / cortex (primary coating) cable. Core made of glass, also made Cladding from glass but material from the different functions as a wave gauide to maintain fiber optics remain in the nucleus. Primary protective coating as a signal from the outside, especially UV from that can cause interference fiber optics. There are 2 types of cable structure :tight-jacket and loose tube.


Structure type tight-jacket

Type loose tube
Construction FO

Laser diode (LD) and Light Emiting diode can be converted from electrical signals a signal light (Electro-optical conversion). Both the oscillator high frequency (≈ 10-e6 GHz) and serves as a noise generator with spectral high bandwidth.

optical transmitter










Specs:


Both the LED and LD have attenuation low on fiber optics. Spectral width Δλ may be a while ranges modulation Δf will be maybe. At the 3 dB insertion loss of the laser diode is only 50% of the power of light transmitter in the fiber optics, in the 15-20 loss Db insertion of LED reduced only a few percent only.

Both the LED and LD have attenuation low Optic Receiver. Two types of semiconductor receiver used in fiber optic communication system:

1. PIN (P-Intrinsic-N).
2. APD ( Avalanche Photo Diode).

As well as the optical transmitter, the optical material also consists of semiconductor. Combined with a transmitter Gallium Arsenide (GaAS), quartz and silica fiber (SiO2) and silica (Si) receiver.

PIN diode
In the PIN diode, optical fiber is placed so that the light received a fall on the intrinsic layer of semiconductor material that placed between the layers and the types of N-type and P-type. Junction diode is formed by coating a layer, this reverse-biased and the amount of cash that flows through junction is determined by intensity light (photon number) in the entry intrinsic layer. Variations in cash that flows through the PIN diode as a result of variations in the intensity of the optical signal is received is very small so that the need strengthening.































Receiver Optical Wave
PIN semiconductor FO
Semiconductor PIN diode
Avalanche photo diode
Have a similar construction and operate the same way PIN diode. However, APD does not need a brace effect on the field in the module recipient. Internal gain of APD to create more sensitive, obtained through the use of reverse-biased voltage on the diode junction high. This produce an electric field in the layer of high intrinsic diode.
















APD diodeAt the time an electron removed because of a photon into the intrinsic layer, electric field will cause electrons to move along the layer and a high speed impact with another molecules and release more electrons, which then move along layer with a high speed. This process is called avalanche breakdown. Benefits of the use of avalanche breakdown is increased sensitivity compared with the PIN diode.

Components receiver is consists of Front End, Linear Channel, Data Recovery.










Optical ReceiverFront End
Photodiode: To change the optical signal into electric current.
Preamplifier: To strengthen the signal for the next.

Linear channel
Main Amplifier: Automatically controlled to limit the output voltage.
Low Pass Filter: Voltage to form a useful balance to reduce noise.

Data Recovery
Decision circuit: To compare the output of the linear channel to the level.
threshold and decide whether the signal is a bit "1" or bit "0".
Circuit Clock Recovery: Synchronous decision-making process.