流动腐蚀方式对石英光纤湿腐蚀特性的影响

Effect of flow etching method on wet etching properties of silica optical fiber

为了获得光滑的腐蚀光纤表面,本文从光纤腐蚀的传质及动力学特性出发,设计了一种流动腐蚀光纤装置。采用质量百分比浓度为12.5%的氢氟酸(HF)溶液,研究了石英光纤的组成成分、腐蚀剂温度和流速对腐蚀速率以及腐蚀后光纤表面形貌的影响。实验结果及理论分析表明:光纤腐蚀速率和表面粗糙度受化学反应速率和传质速率控制;由于光纤纤芯与包层成分不同,导致纤芯腐蚀速率高于包层腐蚀速率;在静态腐蚀条件下,腐蚀速率随温度呈非线性增长,且腐蚀后光纤表面粗糙;在流动腐蚀条件下,光纤腐蚀速率提高,并与温度呈线性关系,腐蚀后光纤表面粗糙度随流速的增加呈现出先减小后增大的趋势;在流速为0.75L/min时,获得了光滑的腐蚀光纤表面。

To obtain a smooth surface of etched-fiber core, a flow etching system was developed based on mass-transfer and dynamic response characteristics in silica optical fiber etching processes. The effects of fiber composition, etchant temperature and flow rate on the etching rate of fibers and the surface morphology of etched-fibers were investigated in the mass percent concentration of Hydroflu- oric Acid （HFA） at 12. 5%, respectively. The experimental and theoretical studies show that the etching rate and the surface roughness of the etched-fibers are controlled by the chemical reaction rate and mass transfer rate. The etching rate of fiber core is higher than that of fiber cladding because of the compositional difference between the fiber core and fiber cladding. In the static etching condition, the increase of the etching rate is nonlinear with temperature, and the etched-fiber gives a rough sur- face. Moreover, in the flow etching condition, the etching rate is improved and is linear with tempera ture, and the roughness of the etched-fiber core increases at first and then of etchant flow rate. The results also show that the etched-fiber core with peatedly obtained with the etchant flow rate at 0.75 L/min. smooth surfaces can be repeatedly obtained with the etchant flow rate at O. 75 L/min.