Fiber Optic Communication

By: Padshah Gul

Reg: Su-12-01-003-006

Semester: 6th

Program: Bs.Telecom

Evolution

• Optical fiber was first developed in 1970 by Corning Glass Works. At the same time, GaAs semiconductor lasers were also developed for transmitting light through the fiber optic cables. The first generation fiber optic system was developed in 1975, it used GaAs semiconductor lasers, operated at a wavelength of 0.8 µm, and bit rate of 45Megabits/second with 10Km repeater spacing.

Basic Principles

• Fiber optic communication is a communication technology that uses light pulses to transfer information from one point to another through an optical fiber.

Optical-Cable Transmission

• A basic fiber optic communications system consists of three basic elements:• Fiber media

• Light sources

• Light detector

Light sources, Fiber media, Light detector

•The light beam pulses are then fed into a fiber optic cable (Media) where they are transmitted over long distances.

•At the receiving end, a light sensitive device known as a photocell or light detector is used to detect the light pulses.

•This photocell or photo detector converts the light pulses into an electrical signal.

•The electrical pulses are amplified and reshaped back into digital form.

Optical-Cable Construction

• Fiber-optic cables are constructed of three types of materials: glass, plastic, and plastic-clad silica (PCS) which has three concentric section.

• Core, cladding and jacket.

Optical-Cable Construction

Optical Fiber Construction

Core – thin glass center of the fiber where light travels.

Cladding – outer optical material surrounding the core

Buffer Coating – plastic coating that protects

the fiber.

Types of Optical Fiber

Single Mode:

 

Multi-Mode:oStep-index –

oGraded Index –

Single Mode:

• Minimum dispersion: all rays take same path, same time to travel down the cable. A pulse can be reproduced at the receiver very accurately.

• Less attenuation, can run over longer distance without repeaters.

• Larger bandwidth and higher information rate

Multimode step-index Fibers

• Inexpensive

• Easy to couple light into Fiber

• Result in higher signal distortion

• Lower TX rate

Multimode graded-index Fiber

• Intermediate between the other two types of Fibers

• Often used in local area networks

Advantages of optical fiber Communication:

• Greater capacity• data rates of hundreds of Gbps

• Smaller size & weight

• Lower attenuation

• Electromagnetic isolation

• Greater repeater spacing• 10s of km at least

Disadvantages of optical fiber Communication

• Higher initial cost in installation

• Interfacing cost

• Remote electric power

• More expensive to repair/maintain

CONCLUSION

At present there are many optical fiber communication links throughout the world without using optical solitons. When we introduce optical solitons as light pulses through the fibers, we can achieve high quality telecommunication at a lower cost. We can expect a great revolution in optical fiber communication within a few years by means of solitons.