Figure 1

Schematic of a fiber gyroscope using part of an existing fiber network (thick red lines). A wave produced by a laser source in the transmitter node is split and sent around the loop in both directions (black arrows). At the same node the waves are received and interfered with, producing the Sagnac signal. $L\text{and}A$ are the loop length and enclosed area, respectively.Reuse & Permissions

Figure 2

Optical layout of the fiber gyroscope. Four waves of equal frequency are propagating around the loop. Full lines denote clockwise propagating waves, and dashed lines denote counterclockwise propagating ones. D1, D2, and D3 are photodetectors at which interference of two waves occurs. Their signals contain information about relative phases and their time variations. ${\Phi }_1$ is the phase from which the fluctuations of the Sagnac phase ${\Phi }_S$ is determined.Reuse & Permissions

Figure 3

Proposed fiber network geometries for the discrimination of area changes. Left: simplest geometry with three gyroscopes I, II, and I-II. The laser waves traveling in these three gyroscopes from the single station are indicated by the red, green, and black arrows, respectively. Right: more complex geometry. Station 1 operates the outer fiber loop enclosing areas $A_{\text{I}},A_{\text{II}}\text{,}\text{and}{A}_{\text{III}}$. Station 2 operates (possibly alternating) the three smaller individual loops I, II, and III. Laser waves are indicated by arrows, but are not color coded. For example, a change in the outer loop area by deformation of the outer loop link subsection $L_1$ can be detected and rejected by correlation with the Sagnac signal from gyroscope I and noncorrelation with signals from gyroscopes II and III. If instead a deformation of the link subsection $l_1$ occurs, this would not appear in the outer gyroscope signal but could nevertheless be detected by anticorrelation between the signals from gyroscopes I and III and noncorrelation between the signals from gyroscope I and gyroscope II.Reuse & Permissions