AdvancedTopic 96 of 101Signals, Control & Comms
Optical fibre communication
Light in glass carries high-capacity data with low loss.
In depth
Optical fibre guides light by total internal reflection: single-mode (9 µm core, long distance) and multimode (50/62.5 µm, short links). Loss ~0.2 dB/km at 1550 nm; dispersion limits bit rate; amplifiers (EDFA), WDM and coherent detection give Tbit/s per fibre. Components: lasers, modulators, photodiodes.
Key points
- Attenuation and dispersion
- DWDM channels
- Splicing and connectors
ExampleA single fibre pair can carry tens of terabits per second with DWDM.
What is Optical fibre communication?
Light in glass carries high-capacity data with low loss.
Why is it important to understand optical fibre communication?
Optical fibre carries enormous data rates over long distances with low loss, which is why it forms the backbone of the internet.
Why does fibre have such low loss?
Glass is extremely transparent at certain infrared wavelengths, so very little light is absorbed over long distances.
What causes dispersion in fibre?
Different wavelengths or modes travel at different speeds, which spreads pulses and limits the data rate over distance.
How is Optical fibre communication used in practice?
Typical applications include connecting data centres with high-speed fibre links, carrying telecom traffic under the ocean and monitoring the strain along a bridge with fibre sensors.
What should I learn before Optical fibre communication?
Study "Satellite communication" first (topic 95 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Optical fibre communication?
Attenuation and dispersion. DWDM channels. Splicing and connectors.
Can you give an example of Optical fibre communication?
A single fibre pair can carry tens of terabits per second with DWDM.
What comes after Optical fibre communication?
The next topic is "Radar basics", which builds directly on this one.
How difficult is Optical fibre communication?
It is classed as Advanced in Signals, Control & Comms (topic 96 of 101). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Signals, Control & Comms.