What is the role of total internal reflection in fiber-optic communication?

Total internal reflection is the key principle that enables light to be guided through an optical fiber. An optical fiber consists of a core with a higher refractive index surrounded by a cladding with a lower refractive index. When light enters the fiber, it strikes the interface between the core and the cladding at an angle greater than the critical angle. At this point, instead of refracting out of the core, the light undergoes total internal reflection and is completely reflected back into the core. This process repeats along the length of the fiber, allowing the light to travel through the fiber without escaping. Because of total internal reflection, the light signal can travel long distances with very little loss of intensity. This makes fiber-optic cables extremely efficient for transmitting data at high speeds over long distances, which is essential for modern communication systems like the internet and telecommunications.