本文对芯中折射率为α分布的双包层单模光纤的传输特性作了详细分析和计算,并且考虑了实际光纤制造工艺(MCVD法)中存在的折射率中心凹陷的影响。根据理论计算值,在国内首次成功地制造了大芯径双包层单模光纤,芯径达14～17μm,比通常的单包层单模光纤提高一倍左右,且弯曲损耗也有明显减小。 In this paper, the transmission characteristics of double-clad single-mode fiber with refractive index α in the core are analyzed and calculated in detail, and the influence of the central depression of refractive index existing in the actual optical fiber manufacturing process (MCVD method) is considered. According to the theoretical calculation, for the first time in our country, a large core double clad single mode fiber with a core diameter of 14 ~ 17μm has been successfully fabricated, which is about one time larger than the conventional single clad single mode fiber with a significant decrease in bending loss .