Long-period Gratings and Multimode Interference in Helical Single-Mode Fiber

Many interesting phenomena in twisted fiber have been reported. In this paper, the twisted single-mode fiber (TSMF) was proposed and studied. It was fabricated by CO2 splicer. Experiments and robust cladding modes resonant theoretical model demonstrated it has transmission dips of long-period gratings. Besides, the light in core will scatter into cladding due to disturbance in core. It will cause multimode interference. A tangential direction theoretical model was put forward to test the experiment characteristic, and was in good agreement with experiment results. In addition, some performance of physical parameters, such as temperature and bending loss response of TSMF are also analyzed. The results indicate that TSMF is a good candidate in sensing and the telecommunication fields.