Improved Coupling Filter Based On Axisymmetric Twin-core Fiber

In order to reduce insertion loss, researchers have proposed an improved coupling filter based on axisymmetric twin-core fiber. The filter uses the method of online monitoring of the output power of the filter, and the cores of two ordinary single-mode optical fibers are separately aligned with a section of axisymmetric non-coaxial twin-core optical fiber with the same core length of L in a dislocation method. One core is fused together. This kind of filter has a small insertion loss, but it needs to precisely align one of the cores of the single-mode fiber and the dual-core fiber, which takes a long time and still has certain difficulties.