Polarization-maintaining Fiber Coupler is One

https://www.meisuoptics.com/polarizationmaintaining-fiber-coupler-is-one-of-the-basic-components-of-high-precision-fiber-sensor.html

The polarization maintaining coupler is a key component to realize the coupling, splitting and multiplexing of linearly polarized light. Its characteristic is that it can stably transmit two orthogonal linearly polarized lights and keep their respective polarization states unchanged, thus becoming key optic devices for various military interference sensors, coherent optical communications, fiber optic gyroscopes, and fiber optic hydrophones etc.

1. Difficulties in the manufacture of polarization-maintaining fiber couplers
The optical fiber coupler is the core component of these optical fiber sensors, and its performance has a great influence on the overall performance of the optical fiber sensor.

The laser interferometry is to hit the helium-neon laser from the side onto the polarization-maintaining fiber, rotate the two fibers separately, and determine the polarization axis direction of the fiber through the change of the interference fringes during the rotation. In this method, the fiber is placed between two polarizers placed orthogonally, and the polarization axis of the fiber can be detected according to the birefringence generated by the stress application part.