11-01-2014, 02:27 PM
Free Space Optical Communication(FSOC) and Its Application
Requirements of a Good Transmission System:
High Bandwidth
Low BER
High SNR
Power efficient
Provide Data Security
Low cost
Easy to install and maintain
Introduction
Free-space optical communication (FSO) is an optical communication technology .
FSO can transmit data, voice or video at speeds capable of reaching 2.5 gbps.
FSO units consist of an optical transceiver with a laser (transmitter) and a photo detector (receiver) to provide full duplex capability .
History Of Optical Communication
The ancient Greeks used light in the battle to send signal
In 1880 Alexander Graham Bell created the ‘Photo-phone’, allowed for the transmission of sound on a beam of light.
German scientist Carl Zeist Jena developed the Lichtsprechgerät 80 (light speaking device) that the German army used in their World War II as anti-aircraft defence units.
The invention of lasers in the 1960s revolutionized free space optics for which Military organizations were particularly interested and boosted their development.
A Few Points about Optical Fiber (OF)
An Indian physicist Narinder Singh Kapani is said to be the ‘Father of Optical Fiber’.
An optical fiber is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair.
It functions as a waveguide or light pipe to transmit light between the two ends of the fiber.
It has four parts- core, cladding buffer and jacket
The phenomenon of ‘Total Internal Reflection’(TIR) is obeyed inside the fiber to keep light propagating through it.
Basic Steps in Optical Fiber Communication
Creating the optical signal involving the use of a transmitter,
Relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak,
Receiving the optical signal and converting it into an electrical signal.
Practical Uses and Application
Communication between Merrill Lynch Brokerage and Wall Street in New York following 9/11 that destroyed normal fiber optic link
Free Space Optics are additionally used for communications between spacecraft.
LAN-to-LAN connections on campuses at Fast Ethernet or Gigabit Ethernet speeds
LAN-to-LAN connections in a city, a metropolitan area network etc
As a safety add-on for important fibre connections (redundancy)
Last-mile bottleneck
Conclusion
FSOC is touted to replace RF communication in every field of science.
With its immense BW and speed, it can achieve a data rate that is never possible for copper wire architecture.
Although it has got some negativities but it is still in its infancy .
Its advantages will surely be made use of in communication replacing OFC and Copper wired communication