The Sagnac interferometer has been principally used to measure rotation and is a replacement for ring laser gyros and mechanical gyros. It may also be employed to measure time-varying effects such as acoustics, vibration, and slowly varying phenomena such as strain. By using multiple interferometer configurations, it is possible to employ the Sagnac interferometer as a distributed sensor capable of measuring the amplitute and location of a disturbance.

The single most important application of fiber optic sensors in terms of commercial value is the fiber optic gyro. It was recognized very early that the fiber optic gyro offered the prospect of an all solid-state inertial sensor with no moving parts, unprecedented reliability, and a potential of very low cost.

The potential of the fiber optic gyro is being realized as several manufacturers worldwide are producing them in large quantities to support automobile navigation systems, pointing and tracking of satellite antennas, inertial measurement systems for commuter aircraft and missiles, and as the backup guidance system for the Boeing 777. They are also being baselined for such future programs as the Comanche helicopter and are being developed to support long-duration space flights.

Other applications using fiber optic gyros include mining operations, tunneling, attitude control for a radio-controlled helicopter, cleaning robots, antenna pointing and tracking, and guidance for unmanned trucks and carriers.