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What is a PM GYRO FIBER?
A PM Gyro fiber (Polarization-Maintaining Gyroscopic fiber) is a highly specialized category of single-mode optical fiber designed to preserve the linear polarization states of propagating light waves, even when the fiber is subjected to mechanical stress, bending, or temperature fluctuations.
Its primary purpose is to serve as the foundational sensing medium in Fiber-Optic Gyroscopes (FOGs). By eliminating polarization cross-talk and phase errors induced by external environmental changes, these fibers enable ultra-precise measurements of angular velocity for critical navigation and guidance systems.
HOW a PM GYRO FIBER Works
The functionality of a PM Gyro fiber relies on intentionally induced mechanical stress to control the behavior of light, functioning in three steps:
Built-In Stress Generation
During the manufacturing process, high-expansion structural elements (such as Panda or Bow-Tie stress-applying parts) are integrated parallel to the fiber core. As the drawn fiber cools, these elements contract differently than the surrounding silica cladding, creating permanent, directional mechanical stress across the core.
Induced Birefringence
This internal stress creates a strong asymmetry in the core's refractive index between two perpendicular axes, known as the fast axis and the slow axis. This phenomenon, called birefringence, forces light polarized along one axis to travel at a distinctly different speed than light polarized along the other axis.
Polarization Decoupling
Because the two propagation modes travel at highly mismatched velocities, they cannot easily exchange energy or mix (cross-talk). When linearly polarized light is launched into one of these axes, it remains tightly confined to that specific orientation throughout the fiber loop, shielding the optical phase information from external perturbations.
