Which data encoding technology is used in fiber-optic cables?

Data is transmitted across a network on media. Modern networks primarily use three types of media to interconnect devices:

Metal wires within cables (copper cable, such as twisted-pair and coaxial cable) – Data is encoded into electrical impulses.
Glass or plastic fibers within cables (fiber-optic cable) – Data is encoded into pulses of light.
Wireless transmission – Data is encoded via modulation of specific frequencies of electromagnetic waves.