Fiber optical cables are used to transmit data over long distances at high speeds using light waves. They consist of thin strands of glass or plastic fibers that are enclosed in protective sheaths.

When data is transmitted through a fiber optical cable, it is first converted into light signals using a device called a modulator. The modulator sends these light signals into the fiber optical cable, which is designed to guide the light signals along its length using a process called total internal reflection.

Total internal reflection occurs because of the way the fiber optical cable is constructed. The cable has a core made of glass or plastic fiber that is surrounded by a cladding layer with a lower refractive index. This difference in refractive index causes the light signals to be reflected back into the core whenever they approach the boundary with the cladding layer at an angle greater than a certain critical angle. This keeps the light signals inside the core and prevents them from leaking out of the cable.

As the light signals travel through the fiber optical cable, they encounter different types of devices that manipulate the light signals, such as amplifiers to boost the signal strength and repeaters to regenerate the signal. When the light signals reach their destination, they are received by a device called a demodulator, which converts them back into the original data format.

Fiber optical cables have several advantages over traditional copper cables, including higher bandwidth, longer transmission distances, and immunity to electromagnetic interference. They are used in a variety of applications, such as telecommunications, internet connectivity, and medical imaging.