The principles of operation of fiber-optic gyroscopes are reviewed. Performance-limiting phenomena are discussed along with methods to reduce their effect on the rotation-rate signal. Current technology and performance of state-of-the-art systems are presented. Finally, a direction of future research and possible applications are indicated.

An overview of fiber-optic gyroscopes

Different explanations for the Sagnac effect are discussed. It is shown that this effect is a consequence of the relativistic law of velocity composition and that it can also be explained adequately within the framework of general relativity. When certain restrictions on the rotational velocity are imposed, the Sagnac effect can be attributed to the difference in the time dilation (or phase change) of material particle wave functions in the scalar (or correspondingly vector) gravitational potential of the inertial forces in a rotating reference system for counterpropagating waves. It is also shown that all the nonrelativistic interpretations of the Sagnac effect, which are unfortunately sometimes found in scientific papers, monographs and textbooks, are wrong in principle, even though the results they yield are accurate up to relativistic corrections in some special cases.

https://iopscience.iop.org/article/10.1070/PU2000v043n12ABEH000830/pdf

The Sagnac effect: correct and incorrect explanations

Large temporal front distortion of femtosecond pulses occurs in lenses having chromatic aberration. The effect is due to the difference between the phase and group velocities. Equations describing the pulse-front delay in singlet lenses, achromats, and compound lenses are presented. The pulse-front delay is several orders of magnitude larger than the broadening caused by group-velocity dispersion in the lens material. Delays occurring in Fresnel-type zone plates are also described.

/pdf/distortion-of-femtosecond-laser-pulses-in-lenses-2kgmxvfbp7.pdf

Distortion of femtosecond laser pulses in lenses

The evolution of optical interferometers into extreme resolution large dynamic range sensors implemented in a guided wave form is discussed. The design and performance of fibre optic interferometric sensors optimised for specific periodic and quasi-steady-state measurands such as rotation, magnetic field, temperature, etc., are described.

https://iopscience.iop.org/article/10.1088/0022-3735/18/12/001/pdf

Monomode optical fibre interferometers for precision measurement

We study the effect of rotation on the propagation of electromagnetic waves in slow-light waveguide structures consisting of coupled microring resonators. We show that such configurations exhibit a new type of Sagnac effect which can be used for the realization of highly compact integrated rotation sensors and gyroscopes.

/pdf/sagnac-effect-in-coupled-resonator-slow-light-waveguide-a52ld4fkip.pdf

Sagnac effect in coupled-resonator slow-light waveguide structures.

We review the kinematic explanation of the Sagnac effect in fiber gyroscopes and recall that the index of the dielectric medium does not have any influence. Furthermore, we present a novel electrodynamic approach that confirms in more detail that the Sagnac phase shift of a ring-waveguide interferometer is the same as for the original Sagnac experiment with plane waves in a vacuum.

H C Leèfovre

Papers

Sagnac effect in fiber gyroscopes