微结构光纤制备过程中不同位置空气孔的形变量分析

Analysis of the shrinkage in size of air holes in different sections during the fabrication of microstructured fibre

根据热传导原理,在拉制微结构光纤(MSF)时,在高温区中,MSF预制棒的包层内不同位置加热的温度也不一样,且由表面往中心方向温度逐渐下降,温度梯度随MSF预制棒下棒速度的加快或包层空气填充率的减少而增大.由于材料的表面张力和黏度系数都是温度的函数,因此将MSF预制棒拉细成MSF时,实际所得到的MSF结构,并非是预制棒等比例的缩小,而是温度越高的空气孔形变量越大.为得到符合设计要求的MSF,就必须将MSF预制棒包层空气孔尺寸按温度变化规律设计,从而消除由于加热温度的非均匀性对拉制的MSF包层空气孔所产生的影响.

According to the heat conduction theory,different sections of the cladding of microstructured fibres（MSF）have different temperature in the high temperature zone during drawing MSF.The temperature decreases gradually from the surface to the central in MSF preform,and the temperature gradient will increase with either the increase of feed speed of MSF preform or decrease of the air-filling fraction.Because both the surface tension and the coefficient of viscosity are functions of temperature,when the MSF preform is thinned to MSF,the actual structure of MSF is not a simple down-sealing of the perform.The shrink size of the air holes will increase as the temperature rises.In order to obtain the MSF as expected,we must design the size of air holes of the MSF preform to vary corectly with the temperature variations,so as to effectively eliminate the effects of uneven heating temperature on the air holes in the cladding of MSF.