Fiber optics gyroscope (FOG) was proposed in 1975 and uses optical waves which propagate in an optical Fiber coil to measure a rotation rate accurately. Fiber optics gyroscope senses variations in angle using the Sagnac effect. However, Fiber optics gyroscope principle is similar to the interference of light which has passed through a Fiber optics coil whose length can be 5 km long.

Fiber optics gyroscope speciously simple design catches full advantage of the interchange principle in the propagation of light. Fiber optics gyroscope is widely used in Fiber optics gyrocompass which is a compass and navigation instruments. Other major applications of Fiber optics gyroscope is remotely operated underwater vehicles, autonomous underwater vehicle, and surveying.