Optical Fibres

Question 1

How do Optical Fibres work?

Answer 1

Use total internal reflection to transmit waves. Has a small critical angle so it is always reflected

Question 2

What are Optical Fibres?

Answer 2

Flexible glass tubes that carry light signals

Question 3

What are Optical Fibres used for?

Answer 3

Endoscopes and communications

Question 4

What happens if the radius of the bend is too small?

Answer 4

Total Internal Reflection cannot take place

Question 5

What are the properties of optical fibres?

Answer 5

High transparent - minimise absorption otherwise amplitudes will reduce the further they travel
Cladding (low refractive index) - reduces light loss from the core (amplitudes reduce)
Small Critical Angle - allows TIR to take place

Question 6

What is modal dispersion?

Answer 6

Happens in a wide core - causes different path lengths
pulses broaden and merge
can’t be interpreted properly
limits speed of communication

Question 7

What is material dispersion?

Answer 7

If white light is used instead of monochromatic
red light travels faster than violet light
pulses broaden (and merge) as violet falls behind
cant be interpreted properly