Optical Fibres Flashcards
How do Optical Fibres work?
Use total internal reflection to transmit waves. Has a small critical angle so it is always reflected
What are Optical Fibres?
Flexible glass tubes that carry light signals
What are Optical Fibres used for?
Endoscopes and communications
What happens if the radius of the bend is too small?
Total Internal Reflection cannot take place
What are the properties of optical fibres?
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
What is modal dispersion?
Happens in a wide core - causes different path lengths
pulses broaden and merge
can’t be interpreted properly
limits speed of communication
What is material dispersion?
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
