Research On The Focal Ratio Degradation Of Large Core Fiber

With the development of astronomical telescope system, the optical fiber, as an important component of the telescope, has already been applied extensively. Transmission and focal ratio degeneration of fiber decide the performance of the whole system in optical fiber telescope.This paper mainly discusses the FRD of step index of refraction, large core and multimode fiber. We also systematically analyze the major factors that lead to the FRD and its influence to the transmission and spectrograph efficiency. According to numerical analysis and experiments, we study the influence caused by the bending that leads to the FRD. Based on the above research, we analyze the disperse extent, excursion of the spot, dispersion characteristic in different directions of the circular spot and the FRD characteristic at misaligning to the center of fiber core based on different bending radiuses. These studies describe the influencing mechanism more systematically and entirely what caused by the FRD when light propagates in bending fibers...