Donot

Optical Communication Concept
R K Gangwar Divisional Engineer(Transmission) BSNL
For circulation to Trainees only

Agenda
• History • Why Optical Fiber? • Applications of Optical Fiber

• Transmission Sequence
• Geometry of Fiber

• Principle of Propagation of Light
• Types of Optical Fiber

For circulation to Trainees only

History
• • • • 1960: Laser invented 1967: New Communications medium: cladded fiber 1960s: Extremely lossy fiber: more than 1000 dB /km 1970, Corning Glass Work NY, Fiber with loss of less than 2 dB/km 70s & 80s : High quality sources and detectors Late 80s : Loss as low as 0.16 dB/km

• •

For circulation to Trainees only

Why Fiber ?
• Many advantages – SPEED: Fiber optic networks operate at high speeds up to the Terabits per seconds – BANDWIDTH: large carrying capacity – Low signal attenuation: Fewer repeaters – RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables. – MAINTENANCE: Fiber optic cables costs much less to maintain – Security

• Extremely difficult to tap a fibre as it does not radiate energy that can be received by a nearby antenna. circulation to Trainees only For

Why Fiber ?
– Security - Being a dielectric • It cannot cause fire. • Does not carry electricity. • Can be run through hazardous areas.

– Low signal attenuation-Fewer repeaters
– Available in Long lengths (> 12 kms)

Less splice points.
– Universal medium Serve all communication needs. Non-obsolescence
For circulation to Trainees only

Disadvantages
• • • • •
–

higher initial cost in installation Interfacing cost Strength: Lower tensile strength Remote electric power more expensive to repair/maintain
Tools: Specialized and sophisticated

For circulation to Trainees only

APPLICATIONS OF OPTICAL FIBER
1. LONG DISTANCE COMMUNICATION BACKBONES 2. INTER-EXCHANGE JUNCTIONS 3. VIDEO TRANSMISSION 4. BROADBAND SERVICES 5. COMPUTER DATA COMMUNICATION (LAN, WAN etc..) 6. HIGH