设计了一种适用于极寒温度(-70℃)条件的耐低温的特种光纤，其结构包括纤芯层、内包层、凹陷包层和外包层.研究了光纤芯层/内包层的相对折射率差与弯曲损耗之间的关系，对比了不同涂覆层模量厚度和对光纤微弯损耗的影响.优化光纤拉丝工艺，获得了一种可长期应用于-70℃极寒温度下，在1 550 nm、1 625 nm波段处附加损耗低于0.01 dB/km的石英光纤.本文研究工作为耐极寒光纤、光纤复合架空地线的制备及产业化提供了可靠的理论与实验依据.

A novel fiber used in extreme low temperature (-70℃) was designed, which includes the core layer, the inner cladding layer, the depression cladding and the outer cladding layer. The relationship between the bending loss and the refractive index difference was studied. By comparing the thickness and modulus of different coating layers, optimizing design of the fiber drawing process, a quartz fiber that can be used in -70℃ for a long time was manufactured. The experimental results show that the additional loss (-70℃) of the fiber at 1 550 nm and 1 625 nm is less than 0.01 dB/km, which provides reliable theoretical and experimental basis for the preparation and industrialization of extreme cold fiber and optical fiber composite overhead ground wire.