本文就大NA石英系光纤制造中如何防止长期存在的预制件炸裂问题,探讨了把芯折射率分布作成渐变型的大NA光纤。用MCVD法制造出了使沉积温度随芯玻璃膜组成改变而变化的大NA(=0.39)渐变型纤维。其结果,研究成功一种使大NA与低损耗并存的预制件制造方法,并实现了在相对折射率差△=3.3%时,损耗为2.49dB/km(测定波长1.67μm)。而且,通过实验明确了GeO_2-P_2O_5-SiO_2及P_2O_5-SiO_2系芯成分与相对折射率差△、和损耗特性的关系,研究了有关传输损耗特性中的瑞利散射损耗、结构缺陷损耗、OH基吸收损耗。在长波长,能够作到很小的瑞利散射损耗和由OH基引起的吸收损耗,大NA光纤在长波长的优越性明显了。当△=3%以上时,结构缺陷损耗急剧增加。还明确了改进收棒方法的必要性。对于弯曲损耗,求出了与弯曲次数、弯曲半径、△之间的依赖关系,设弯曲半径为R,弯曲损耗可用(1/R)~(1.2)exp~(-k△)来表示。 In this paper, how to prevent the long-standing preform from exploding in the manufacture of large-NA quartz optical fiber is discussed. The core refractive index distribution is discussed as a large NA fiber with gradual change. A large NA (= 0.39) graded fiber that changes the deposition temperature with the composition of the core glass film was made by the MCVD method. As a result, the successful development of a preform manufacturing method in which large NA and low loss coexist has been studied, and the loss was 2.49 dB / km (measurement wavelength: 1.67 μm) at a relative refractive index difference Δ = 3.3%. Moreover, the relations between the composition of the core and the relative refractive index difference and the loss characteristics of the GeO_2-P_2O_5-SiO_2 and P_2O_5-SiO_2 system cores have been experimentally confirmed. The influences of the Rayleigh scattering loss, the structural defect loss, the OH group Absorption loss. At long wavelengths, small Rayleigh scattering losses and absorption losses caused by OH groups can be achieved, and the superiority of large NA fibers over long wavelengths is evident. When △ = 3% or more, the structural defect loss increases sharply. It also clarified the need to improve the stick collection method. For the bending loss, the dependence on the number of bending, the bending radius, and the? Is obtained. Let the bending radius be R and the bending loss be expressed by (1 / R) ~ (1.2) exp ~ (-kΔ).