Cladding
Cladding is added to the outside of an optical fibre to reduce the amount of light that is lost. It does this by giving the light rays a second chance at TIR as seen in the diagram.
It does increase the critical angle but the shortest path through the optical fibre is straight through, so only letting light which stays in the core means the signal is transmitted quicker.
Consider the optical fibre with a refractive index of 1.5…
Without cladding n2 = 1
With cladding n2 = 1.4
If the cladding had a lower refractive index than the core it is easier for light to travel through so the light would bend away from the normal, Total Internal Reflection.
If the cladding had a higher refractive index than the core it is harder for light to travel through so the light would bend towards the normal, Refraction.
| Section 3 | Interference | |
|---|---|---|
| Lesson 6 | ||
| Learning Outcomes | To be able to explain what interference and coherence is | |
| To be able to explain Young’s double slit experiment and a double source experiment | ||
| To be able to use the equation to describe the appearance of fringes produced | M.BENYOHAI |