Total Internal Reflection (TIR)
What is total reflection?
Total internal reflection refers to the phenomenon where when light travels from a medium with a higher refractive index to a medium with a lower refractive index , if the angle of incidence reaches a certain degree, the light no longer refracts out but is completely reflected back into the original medium , just like bouncing back after hitting a wall.
How to make Total Internal Reflection Happen?
For total internal reflection to occur, two conditions must be met:

Total Internal Reflection in Fiber Optics
In fiber optics, total internal reflection (TIR) happens like this:
- Optical fibers have a core (inner part) with a higher refractive index than the surrounding cladding.
- When light travels through the core and hits the core-cladding boundary at a steep enough angle, it doesn't leak out into the cladding.
- Instead, the light bounces back into the core, reflecting repeatedly off the boundary as it moves down the fiber.
- This "trapping" of light inside the core lets it travel long distances without significant loss.
