The interferometric fiber-optic gyroscope (I-FOG) is today an important technology for many civilian and military applications such as inertial navigation and guidance systems for automotive, aircraft, and space industries; satellite antennas pointing and tracking; mining and tunneling operations; and helicopter attitude control. It brings the advantages of solid-state technology (guided-wave optics and low-voltage low-power electronics) with a cost reduction that enlarges the application domain.
The I-FOG is based on the Sagnac effect, which produces in a ring interferometer a phase difference proportional to the dot product of the rotation rate vector by the area vector enclosed by the optical path, and takes advantage of single-mode optical fiber as the propagation medium. Several critical system components and design characteristics affect the I-FOG performance: the coil optical fiber; the active source; the passive and integrated-optics components; the optical circuit configuration for reciprocity; and the detection schemes.
In this application, we demonstrate the design of an I-FOG. Figure 1 illustrates the schematic. The system can be divided into three main sections: the source, the I-FOG fiber optic loop, and the signal detection.