Optical Fiber
A flexible, transparent glass or plastic fiber that transmits light signals across long distances via total internal reflection.
Governing formula
NA = √(n_core² - n_cladding²)
SI unit
dB/km
In depth
Consists of a high-index core ($n_1$) enclosed by a lower-index cladding ($n_2$). Light guided inside core reflects at angles $θ > θ_c$ without escaping.
Examples in the real world
Global fiber-optic telecommunication cables carrying gigabits of internet data per second across ocean floors.