Application of fused tapering optical fiber coupler in mode selective couplers and sensors: A review

Among the many fabrication methods of optical fiber couplers, fused tapering technology offers distinct advantages in low loss, simplicity, and flexibility. In recent years, with the continuous refinement of fabrication technology, the high-precision emerging applications of fused tapering optical fiber couplers, such as mode conversion and optical coupled sensing, have become remarkable new research directions. Silica-based optical fibers are primarily used for fabricating fused tapering fiber couplers, while novel materials like polymer optical fibers are increasingly integrated into fused tapering technology. This paper focuses on fused tapering optical fiber couplers and summarizes their application in mode selective couplers and sensors. A series of comparisons are performed, and a brief outlook on future development trends is presented. This paper aims to provide a reference for application research of mode selective couplers and sensors based on fused tapering optical fiber couplers.