Fiber Optic Coils for Gyroscopes

Description

Fiber coils form the heart of fiber optic gyroscopes. Two counter-propagating optical signals generate a phase difference inside the fiber coil proportional to the rotation rate that the coil experiences, a phenomena known as the Sagnac effect. The Sagnac effect is dependent on the length and diameter of the fiber coil. As the length or the diameter of the fiber coil is increased, the sensitivity of the FOG also increases.

Fiber coils made of stress-induced high-birefringence polarization-maintaining (PM) single-mode fiber give the best performance in FOGs. In PM fiber, most of the power is maintained polarized along the fiber polarization axis, avoiding signal fading. Fiber coils should be carefully wound by special winding machines to minimize thermal and stress gradients and asymmetries. The performance of FOGs is mostly limited by thermally induced bias errors known as the Shupe effect, caused by time-dependent temperature gradients along the fiber coil.

Together with our partner OZ-Optics we have the capability to design, manufacture and test fully customized fiber coils. OZ-Optics uses symmetrical winding methods such as quadrupole winding in order to reduce the Shupe effect. Customers can also request octupole or hexadecopole winding patterns to obtain more sensitive fiber coils. Depending on customer requirements, fiber coils can be manufactured in a wide range of lengths and in different sizes. OZ-Optics offers the most optimum solution by using different adhesives suitable for the mechanical properties of different fiber types.
Today, fiber optic gyroscopes are widely used in civilian applications such as autonomous vehicles as well as military applications. OZ-Optics offers low-dimensional fiber coils for gyroscopes of autonomous vehicles. Fiber with coating diameters of 100 µm and 135 µm can also be requested. Moreover, OZ-Optics’ winding machines wind fiber coils with high accuracy and low tension to minimize coil stress.