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OFC system; pros and cons over metal wire

Short answer

A fibre system comprises a transmitter (LED/laser), fibre, amplifiers/repeaters and a receiver (PIN/APD). Advantages over metal wire: enormous bandwidth, very low loss (~0.2 dB/km), immunity to EMI, small size and electrical isolation. Disadvantages: higher installation and splicing skill required, fragility, inability to carry power, and need for O/E conversion.

Draw the optical fiber communication system. What are the advantages and disadvantages of optical fibers over metal wire communication?

Optical fibre communication system

 +--------+   +----------+   +---------+
 | Info   |-->| Electr.  |-->| LED /   |
 | source |   | Tx/driver|   | laser   |
 +--------+   +----------+   +----+----+
                                  |
     ===== fibre cable (splices, connectors,
     =====  repeaters / optical amplifiers)
                                  |
 +--------+   +----------+   +----v----+
 | Dest.  |<--| Amplifier|<--| PIN/APD |
 |        |   | /decision|   | detector|
 +--------+   +----------+   +---------+

The message is converted to an electrical drive signal, which modulates the intensity of an LED or laser. The light travels through the fibre by total internal reflection, is boosted by repeaters or optical amplifiers on long routes, and is converted back to current by a photodiode. The receiver amplifies and regenerates the signal for the user.

Advantages over metal wire communication

Advantage over copper wireReason
Huge bandwidthOptical carrier ~200 THz; Tb/s on one fibre
Low loss~0.2 dB/km, repeaters every 80–100 km (copper: ~2 km)
Immune to EMI and crosstalkLight is not affected by electrical noise or lightning
Electrical isolationGlass is an insulator; no ground loops or sparks
Small size, light weightFibre is ~125 µm; a cable is much lighter than copper
Signal securityNo radiation; tapping is hard to do undetected
Raw materialSilica (sand) is plentiful; copper is costly
Long life, corrosion-freeGlass does not corrode

Disadvantages compared to metal wire

DisadvantageReason
Costly installationFusion splicers, OTDR and skilled staff needed
FragileGlass breaks if bent tightly or crushed
Difficult joiningMicron-level alignment for splices/connectors
No power feedingCannot carry DC power to repeaters/terminals like copper
Optical–electrical conversionExtra transmitter and receiver circuits needed
Repair is harderLocating and fixing a cut needs special tools

✓ Answer checked by Claude Opus 5.5 (high effort)

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