The impact of fiber fusion on the focal ratio degradation and transmission

We report results of the impact of fiber fusion splicing on Focal Ratio Degradation and transmission loss. Experiment use formed beam methods at wavelengths between 400 and 1000nm of PolyMicro fiber. We test at five input f-ratio (f/2.5, f/3.75, f/5, f/75, f/10) conditions, the influence of fiber fusion splicing on FRD respectively, and test at f/5 input f-ratio condition, the influence of fiber fusion splicing on fiber transmission loss. A precision test system was designed to reduce the system error and human error. The measurement accuracy of the system reaches micron scale. The fiber end surface was prepared by large core fiber cutter, grinder and fusion splicing workstation. The fiber surface roughness is less than 1 micron and the surface angle is less than 0.1 deg. By optimize the cutting and polish process, adjusted the fusion splicing parameters, a satisfactory results of optical fiber fusion splicing obtained in the laboratory. The maximum transmission increase caused by the fiber fusion splicing is less than 2%, average value is less than 1%; while the maximum FRD increase is less than 0.16 degrees. Our results indicate that fiber fusion splicing technology can be adopted for repair failure optical fiber, replace the fiber clips and astronomical instrument construction. Fiber optic fusion splicing technology has been used successfully in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) optic fiber system.