waves Flashcards
1
Q
what is modal dispersion?
A
caused by light rays entering the optical fibre at different angles (both types of dispersion cause pulse broadening)
2
Q
what is material dispersion?
A
caused by different wavelengths of light experiencing different amounts of refraction (both types of dispersion cause pulse broadening
3
Q
what is absorption?
A
when some of the signals energy is absorbed by the material that the fibre is made from
4
Q
what causes electrical interference?
A
- electromagnetic radiation from external sources
- electromagnetic induction
5
Q
name the advantages of using an optical fibre instead of copper wire
A
- signal carry more information as light has a high frequency
- light doesn’t heat up fibre
- there is no electrical interference
- fibre optic cables are cheaper
- signal can travel a long way quickly with minimal signal loss
6
Q
Describe the structure of a step-index optical fibre outlining the purpose of the core and the cladding.
A
- Core is transmission medium for em waves to progress
- Cladding provides lower refractive index so that total internal reflection takes place
- And offers protection of boundary from scratching which could lead to light leaving the core.
7
Q
what is a single mode fibre?
A
a fibre that only lets light take one path
