基于下陷内包层设计的大芯径掺氟光纤表征及性能

Characterization and Properties of Large-core Fluorine-doped Fibers Based on Depressed Inner Cladding Design

采用体式显微镜、扫描电子显微镜、拉曼光谱表征了不同氟浓度、波导结构条件下光纤预制棒锥区及光纤的表面形貌与微观结构,用光纤综合参数分析仪、自制输出激光刀头分析了大芯径掺氟包层光纤的损耗、激光传输效率.结果表明:随着氟含量的升高,氟挥发现象愈加明显,传统大芯径掺氟包层光纤表面产生的裂纹、凹坑等缺陷增多,光纤损耗略有增加,激光传输效率下降;采用下陷掺氟内包层设计有效抑制了大芯径掺氟包层光纤制备过程中的氟挥发、析晶现象,1200 nm波段光纤损耗为3.99 dB/km,平形和球形光纤2μm波段的激光传输效率分别达到88.9%和88.4%,性能明显高于传统结构光纤.

The surface morphology and microstructure of fiber preform taper zones and fibers with different fluorine content and waveguide structure were characterized by stereomicroscopy,scanning electron microscopy and Raman spectroscopy.The loss and laser transmission efficiency of large-core fibers with fluorine-doped cladding were analyzed by fiber analysis system and self-made output laser probe.The results show that the fluorine volatilization phenomenon becomes more obvious with the increase of fluorine content.As a result,the surface defects of traditional large-core fibers with fluorine-doped cladding increase,such as cracks and pits.Simultaneously,the fiber loss increases slightly and the laser transmission efficiency decreases.Moreover,the fluorine volatilization and crystallization during the fabrication process of large-core fibers with fluorine-doped cladding are effectively suppressed through subsidence fluorine-doped inner cladding design.Thus,the fiber loss at 1200 nm is 3.99 dB/km,and the laser transmission efficiency at 2μm of flat and spherical fibers is 88.9%and 88.4%,respectively.It can be obviously seen that its property is better than that of traditional fibers.